Theorycraft 101: 5.4 Trinkets

Blizzard’s pattern of trying to make more interesting raid trinkets in MoP has provided a lot of interesting theorycraft material. As in past Theorycraft 101 posts, the goal is here both to give theorycrafters some useful conclusions and equations to save them the trouble of reinventing them independently, and to give everyone some general information that helps them evaluate these new bonuses when selecting items.

Item Budgets

In general, the amount of any stats budgeted to a certain slot scales like:

V cdot Q^I
  • V is the budget value controlling how many stats that item slot gets compared to other slots.
  • Q is a constant equal to the 15th root of 1.15.
  • I is the item’s ilvl.

Often a more convenient way to think of this, especially when dealing with trinkets, is to use ilvl 463 as a baseline. The reason is that most trinket procs are coded into the spelldata with ilvl 463 values (which is the pre-raid baseline for MoP), and then scaled from there on any individual item based on its ilvl. The Int proc on Nazgrim’s Burnished Insignia, for example, is this this spell. So in general, since looking up the ilvl 463 value for any proc/bonus on Wowhead is easy, you can think of the value at higher ilvls as:

V_{463} cdot Q^{(I-463)}

or

V_{463} cdot 1.15^frac{I-463}{15}

This explains, for example, how the 5084 Int on the proc linked above becomes 11761 Int (i.e. 5084*1.15^6, with a slight deviation due to rounding) when applied to an item that’s ilvl 553 (90 ilvls above 463). Sites like Wowhead will correct for those minor rounding issues so they can exactly match in-game values, but we don’t have to worry about them here.

A lot could be said about item budgets, but I wanted to give the overview here so you have the context on what you should expect from a trinket at various ilvls. A handy factoid is the amount of a passive stat a trinket has at normal budgeting: it’s 847 at ilvl 463, or 1959 at ilvl 553. In other words, the most vanilla possible ilvl 553 raid trinket would have 1959 of a primary stat and 1959 of a secondary stat (or 1959*1.5=2939 in the case of Stamina). Real trinkets will replace one or the other (or both) of those with special bonuses, but that 1959 (or whatever it is at the ilvl you’re looking at) is the basis for comparison.

To work a brief example, see Purified Bindings (553). Note that 11761 Int is just about 1959*6, so the trinket is exactly on-budget if the proc is active 1/6 of the time. Since it has a 20 second duration, you’d expect it to proc every 120 seconds. The 115 second ICD is intended to produce this result and have the trinket match the budget that a passive Int trinket would have.

But you came here to talk about more interesting bonuses than stat procs, so without further ado:

Amplification

Amplifies your Critical Strike damage and healing, Haste, Mastery, and Spirit by X%.” (3.03% at ilvl 463, 7% at ilvl 553, 9% at ilvl 580).

At first blush, this increases the value of all your secondary stats by X%. So if you have 30,000 secondary stats on your character sheet and wore an ilvl 553 Amp trinket, it would be very similar to a trinket with 2100 passive secondary stats (placing it slightly above the par of 1959 in this example). Two quirks:

  • It amplifies Spirit but not hit rating, which is a slight asymmetry across caster classes that I think is an oversight.
  • It increases crit bonus rather than crit chance, which makes things slightly more complicated.

Crit bonus effects have some odd stacking properties. The easiest way to think of it is is that when you crit for 200%, there are two components: the 100% “normal damage” and then 100% “critical damage.” Other than the crit meta, which obeys an idiosyncratic rule* but is irrelevant in T16 due to legendary metas, crit bonus effects all apply multiplicatively to the “critical damage” portion only (including Amp, Skull Banner, and Elemental Fury).

Long story short, the crit bonus provided by Amp causes you to do X% more “critical damage” overall. This does in fact increase the value of your crit rating by X%. But crit chance comes from sources other than rating, and the value of that other crit is also increased by X%. So the easiest way to evaluate this bonus is to:

  1. look at your total raid-buffed crit chance,
  2. imagine that it all came from rating (in most cases, multiply the % by 600), and
  3. take X% of that rating.

Putting it all together, say the total of my haste, mastery, and Spirit were 20,000, and my raid-buffed crit were 35% (16.7% from 10,000 crit rating, and 18.3% from other sources) and I had a 553 Amp trinket (7%). I’d evaluate this part of the trinket as being worth 1,400 stats from haste/mastery/Spirit, and 35*600*7% = 1470 from crit, for a total of 2870, significantly above the expected budget of 1959 secondary stats.

Since the other half of the Amp trinket is, in all cases, a primary stat proc that is right on budget, it is looking like a very strong trinket numerically. It will be even more so for classes with very high effective crit chances due to class mechanics, such as Elemental Shaman. The only important caveat is that is that Prismatic Prison loses a little value for healers because having all of the Int delivered as a high-value high-ICD proc is poor for healing purposes.

*The crit meta increases the “critical damage” in such a way that the total damage will have increased by 3%, before other crit bonuses. Now that every class has a 100% base crit bonus, the crit meta essentially works by increasing it to 106%.

Multistrike

Your heals have a X% chance to trigger Multistrike, which causes instant additional healing to your target equal to 33% of the original healing done.” (6.05% at ilvl 463, 14% at ilvl 553, 18% at ilvl 580)

This is the simplest new bonus. Aside from issues like pets, it’s a straightforward X/3% increase to your damage or healing output. I want to emphasize that this is not an RPPM or ICD effect, simply a plain fixed % chance to occur on any damage/healing event.

The only issue is comparing, for example, 4.67% damage/healing (14%/3) to 1959 secondary stats. I’ll leave that up to individual class modelers, but if you note that 1959 secondaries is, for example, 3.26% crit, you can see that Multistrike is generally looking to be in a good position.

Cleave

Your heals have a X% chance to Cleave, dealing the same healing to up to 5 other nearby targets.“ (1.34% at ilvl 463, 3.11% at ilvl 553, 4% at ilvl 580)

Exactly the same as Multistrike, with the twist that output depends on the number of nearby targets other than your main target. The only important note is that it’s tuned so that, if it hits one added target, it’s 2/3 as strong as Multistrike. For example at ilvl 553, 3.11% is 2/3 the value of the 4.67% output you’d have gotten from Multistrike.

So this trinket is dead even with Multistrike when it hits, on average, 1.5 added targets. In situations where it can regularly hit 5 targets, it is far above budget, and in situations where you are attacking a lone target it is useless. The ramifications of this are obvious, but the rule of thumb that it surpasses a “normal” trinket at around 1.5 splash targets should help you decide when to use it. For 25-man raid healers, I suspect you are very often going to be healing targets who have more than 1.5 other people nearby, except at enforced spread fights.

Cooldown Reduction

Increases the cooldown recovery rate of six of your major abilities by X%.

(17% at ilvl 463, 39% at ilvl 553, 50% at ilvl 580, in each case reduced by half on the tank version)

There’s not too much to say about this in terms of item budgeting, since its benefits are based on the vagaries of each particular class rotation, and I imagine the tuning was done ad hoc. Consult your class’s spreadsheet expert. I just want to correct a common misconception about how the bonus works.

50% CDR does not mean you can use the ability twice as often. It’s exactly analogous to the way haste works, it reduces the cooldown to 1/1.5 = 67% of where it started. So in the end, you can use the ability 1.5 times as often over the course of a fight, not twice as often. Since X% CDR means you can use the effect X% more times in the long run, the benefit is generally linear as the budget increases, as it should be.

This chart lists the affected abilities for each class, in case you need. The trinket doesn’t exist for Int users in this tier.

Other Tanking Effects

I’m not going to say too much about Juggernaut’s Focusing Crystal and Rook’s Unlucky Talisman. They have unique effects that can’t be compared in an apples-to-apples way against 1959 primary or secondary stats. I simply want to note that their inherent % bonuses follow the usual item budget rules just like everything else discussed here. As you upgrade through ilvls, these effects will increase in same way that any stat allocation would (because, as discussed above, all trinket procs/effects are built into the ilvl scaling mechanism now).

This does raise an interesting issue I want to touch on, but a full analysis will be for another post. For a bonus like Juggernaut’s, which is based on a flat % of your overall damage output, there’s a question of whether the overall benefit the trinket gives is actually scaling quadratically with your stat growth. Scaling is inherently confusing and I do want to make a post about it overall, but the basic thrust is that normally as you go up in ilvl, each item has more stat points, and each stat point is worth more because your totals of other stats have increased. It’s left as an exercise to the reader how this logic applies to effects that are based on a % of your other stats such as Juggernaut’s and Amplification.

RPPM

I’ve reviewed the math of RPPM in two prior posts, but this is a good time to note the updates for 5.4.

Every 5.4 RPPM trinket is 0.92 RPPM with a 10-second ICD (except that Ticking Ebon Detonator is 1.00).

Also, for reasons described by Blizzard in this post, haste no longer increases the RPPM of most trinkets, with the only T16 exception being Dysmorphic Samophlange.

A 10-second ICD produces an interesting player-favorable quirk. Since the procs are all 10 seconds long, it prevents overlaps that waste uptime. But since RPPM chance “pools” for 10 seconds (as described in earlier posts), blocking out procs for a 10 second period actually does not impair your overall proc chance in any way. In this case you do get the best of both worlds–the same number of procs you’d have normally, but arranged so that there are no overlaps.

To be on-budget, these trinkets whose procs are all 6 times the value a passive stat trinket would need to have 1/6 uptime. With a 10 second proc duration, you’d think all you need is 1.00 RPPM on all trinkets to be on par. The only quirk to this is that the “bad luck protection” system adds about 13% to proc rates in reality (as discussed in the previous post). Blizzard, slightly generously, has started discounting RPPM rates by around 9% to account for this. This results in a proc rate of 0.92 on all trinkets. Except that for some reason on Ticking Ebon Detonator, the they reduced the proc value by 9% instead (1069 per stack at ilvl 553, instead of 1176).*

Given this information–0.92 RPPM, no haste, 10s duration and no overlaps, uptime for most T16 trinkets is much simpler than it used to be. It will always be simply 1.13*0.92*10/60, or 17.33%. In the case of Samophlange, multiply further by your haste factor to get your final uptime.

Long story short, all RPPM trinkets in 5.4 have an average value that’s very close to equivalent to the passive budget. Essentially always, it’s a proc with 6 times the stats a passive trinket would have and an uptime of around 1/6. The only important exception is Samophlange, which gets a haste multiplier on top of the usual budget.**

*Note that Detonator, Samophlange, and Talisman all have per-stack values that are 1/10 of what a “big” RPPM proc values at the same ilvl would be. However, the actual mean stack height over the course of the proc is 10.5, not 10. The same is true for Black Blood, which has a mean stack of 5.5. This amounts to a free 5% added value to the first three trinkets, and 10% on Black Blood.

**I just want to note since the question is posed so often: just as Samophlange is pegged pretty close to its correct budget + haste, the same was true for Horridon’s Last Gasp. Any nontrivial ilvl jump from Horridon’s to Samophlange is likely to be a clear upgrade.

RPPM on the Pull

Starting in 5.4, for purposes of the “bad luck protection” described in earlier RPPM posts, the moment a raid encounter starts, your RPPM procs all behave as though 120 seconds have passed since the last proc.

Given the formula at the end of this post, any trinket or other RPPM effect with a mean proc time of 45 seconds or less will be guaranteed proc on the pull. This corresponds to RPPM of 1.33 or higher (including haste if it applies). Procs that are close to that value will be very likely to proc within the first few seconds.

A 0.92 RPPM trinket will begin each fight with a significant bonus (just about double it’s usual proc rate). It will have a 31%* chance to proc on your first attack, and if that fails, roughly a 35% chance to proc within the first 10 seconds of combat.

Hearthstone Probabilities and the Monty Hall Effect

The Monty Hall Problem

A certain probability puzzle is well-known in math circles for its unusual ability to cause people to refuse to believe the answer when it is explained to them. It’s usually known as the “Monty Hall problem” (after the host of Let’s Make a Deal):

Monty Hall has given you a choice of three identical doors. Behind one is a car and behind the other two are goats. You choose a door, but before it’s opened to reveal your prize, Monty adds a twist. He opens one of the other doors to reveal a goat (he always does this to add to the suspense). He then offers you the choice of staying with the door you chose, or switching to the remaining unopened door. Should you stay, or should you switch, and what’s your chance of winning in either case?

The answer is surprising to most: switching doubles your odds of winning the car (2/3 chance of winning, as opposed to 1/3 if you stay). The key fact is that Monty’s knowledge of which of the other doors (if any) was a car causes him to always remove a goat from the prize pool. The chance that the initial door you chose contained a car was 1/3 to start, and it’s unchanged by Monty’s ritual. But if the car was behind either of the other two (2/3 probability in total), Monty will remove the losing door and leave the winning one, and switching will win.

(If you don’t buy that the probability is anything other than 50% when everything started out equal and there are now two doors remaining, there are myriad sources on the internet trying to explain in different ways).

The Jaina Proudmoore Problem

Let’s say it’s late in the Hearthstone game and you’re about to try playing your bomb legendary. You’re pretty sure you’ll win if it sticks for a turn, but if it gets answered immediately you might be hopelessly behind. You want to guess whether your opponent Jaina is holding the Polymorph you know she has in her deck (assume for the moment she only has 1 for simplicity; the same concept applies with 2 but the math is more intricate). Her hand has 4 cards, and you mouse over her deck and see she has 16 cards left. After her draw next turn, 5 of 20 unseen cards will be in her hand, so you’d think she had a 25% chance holding the card.

Monty Hall, however, tells you differently. Even though she only has 5 cards in her hand next turn, she’s been selecting out non-Polymorph cards and playing them all game. Just as Monty selected out non-winning doors and removed the pool, making the remaining doors of the ones he could have chosen more likely to be winners, Jaina has been casting non-Polymorph cards from her hand, making the ones she’s left in her hand more likely to be Polymorphs.

For now consider the simplest case, where nothing had been cast so far this game that Jaina would have been likely to Polymorph. Applying the logic from above, there’s a 50% chance that the Poly started the game in the bottom 15 cards in the deck, and that probability has not been changed by any subsequent events. There must, then, be a 50% chance that it’s among the 5 cards in her hand. Quite a significant difference from the 25% that seemed completely intuitive before considering this effect.

Complexities

An important subtlety is that Jaina might not be as selective as Monty. Monty never prematurely revealed a car, but Jaina may have cast a Polymorph before the critical turn, if she had it and the game state called for it. The assumption above that the game state on prior turns never looked like one that would have drawn a Polymorph elides a deep point of probability, namely, the mysterious way that Jaina’s/Monty’s selectivity shifts probability between chosen and unchosen cards/doors. I think getting into the depths of how that happens might be beyond the scope of this post, but for now observe the following.

If you know Jaina is going to save her Poly for your bomb no matter what (and this might not be a bad assumption in a constructed card game where people are familiar with each other’s decks), then the situation is identical to Monty Hall: the probability in the above example would have been 50%. But if you made the opposite assumption, that Jaina is not smart and dispenses cards from her hand at random (ignore the vagaries of the mana curve for the moment), the probability would in fact be the 25% we naively estimated at the start. The best way to see the difference is to really understand why the answer to the Monty Hall problem is what it is. It might also be helpful to look at that bit of logic from the end of the previous section (about the 50% chance that Poly started in the bottom 15 cards of the deck) and try to see why it doesn’t apply in the case of the Jaina that plays randomly.

The other complexity is what I alluded to at the start: the arithmetic is more complicated with two Polymorphs in the deck (but as I said, the logic is unchanged). To work the same example with two Polymorphs:

  • The naive estimate is that out of 20C2 (20 choose 2, referring to combinations) places the Polys could be, 15C2 choices have them in the bottom 15, so the chance of having one in hand is 1-(15C2 / 20C2), which evaluates to 17/38, or around 45%.
  • The Monty-corrected estimate would be that out of 30C2 possible placements at the start of the game, 15C2 have them undrawn in the first 15 cards, so the chance of having one in hand is 1-(15C2 / 30C2), which evaluates to 22/29, or around 76%.

The result is the same as before, a much higher chance in the latter case.

Here is a full table of the probabilities for various deck and hand sizes, for reference:

Dropbox Link

Conclusion

The probability subtleties discussed at the beginning of the last section mean that guessing the probability that your opponent has a certain card is never an exact science. It depends on your judgment of how likely it would have been for them to use it at an earlier point in the game if they’d had it. The Monty Hall effect applies most strongly when it is highly unlikely or impossible (for example due to mana cost) that the card in question would have been played already. Where it applies, it causes the probability of the card being in your opponent’s hand to be substantially higher. So it’s both practical and perhaps fascinating to realize that you can’t rely on what you thought you knew about probability: all unseen cards are not equally likely to be the card you care about.