Path of Exile - Game Mechanics Q&A

Grinding Gear Games recently encouraged their community to send in their questions regarding some of Path of Exile's more obscure mechanics. And now, we can check out the team's answers to those questions over here. If you wouldn't mind peeking under the hood of GGG's free to play action RPG, you should definitely check the article out.

Here's a couple of questions to get you started:

Does Rupturing's "Bleeding on [ruptured enemies] expires 25% more quickly" affect bleeding in the same way as "Bleeding you inflict deals damage x% faster" mods? Does it stack multiplicatively?

Not quite, but the total effect of rupture is similar despite these applying to different things at different times. Modifiers that cause ailments to deal damage faster modify the damage per second multiplicatively (just like a "more damage" modifier), and apply the inverse modification to the duration, so that the total expected damage of the ailment stays the same. Multiple 'deal damage faster' modifiers stack additively with each other.

Modifiers that affect how quickly things expire do not affect the magnitude of the effect at all, and technically do not modify the duration, they make time be tracked differently for that effect. The most common example is Temporal Chains, which you can see in-game does not affect the numerical duration of buffs/debuffs on you, but makes their timers tick down more slowly.

If you inflict Bleeding that would deal 100 damage per second for the default 5 seconds, but have "Bleeding you inflict deals damage 25% faster", that applies 25% more damage per second, and the inverse of this modifier to the duration, resulting in inflicting a bleeding that deals 125 damage per second for a 4 second duration; the total expected damage is still 500. These are the values applied to the enemy in the debuff.

If that enemy is Ruptured, they have 25% more damage taken from bleeding, and the bleeding expires 25% more quickly. So assuming no other modifiers, they would be taking 156 damage per second, and the Bleeding debuff's "4 second" timer would tick down faster, resulting in it expiring after only 3.2 real seconds have passed, and thus dealing a total of 499 damage - 1 having been lost to rounding.

Note that the modifiers from Rupture are dynamic - a bleeding enemy starts taking more damage when they become Ruptured and ceases to do so when Rupture expires, and similarly, a bleeding enemy that becomes ruptured will have the timer on their bleeding debuff speed up, and return to normal speed if rupture is removed.

When mines are detonated while wielding Tremor Rod with a max mines of 20, should the detonated chain be 20 or 40 mines long? Is this dependent on the re-arming time of the mines? If more mines are thrown during the duration of the detonation sequence will those mines delete existing mines like they would before they were detonated, or can re-arming mines not be deleted?

It's mostly dependent on the cast time of the spell the mines use, although re-arming time is also a factor, as is how they're placed. Mines cast spells (or use attacks) just like players do, which takes the cast time of the spell or attack time of the attack. They are "front-loaded" such that the effects of the skill happen right near the start of this time so most of the cast time for mines is follow-through rather than build up, but the total cast time stays the same, and unlike players mines can't try to animation cancel to skip part of the animation. Once a mine finishes casting it's skill, it either immediately dies or starts to re-arm. Re-arming, just like initially arming the mine before it can use a skill the first time, takes a base time of 0.5 seconds, affected by modifiers to mine arming speed. Only after both of these are done can it be detonated to use the skill again.

At the point a mine is detonated, it looks around it for other mines in range to add to the detonation sequence. These must be in-range of the detonating mine, and must be ready to use their skill at that time.

Mines that are alive always count towards the limit and will be replaced if you create too many. The only time a mine stops counting towards that limit is when it dies.