The proc provides -20% resistance on your target, and has a 20% chance to go off each time the power it's slotted in is used (for clicks, anyway, which are all a PB can slot it in). The proc's effect used to be bugged to have an infinite duration, but that has been fixed and the debuff now lasts 10 seconds.
The effect does not stack with itself, at least not from the same user. It has been said that it may be able to stack from both the player and a pet, or two different players, but I'm not sure about that. However, it still may be useful to slot the proc into multiple attacks, simply to increase the chances of the debuff being in effect continuously. In all cases, it's usually the best to slot it first into the attack you use most often, simply to give it the most chances to go off. After that, slotting it in additional powers can better your odds of keeping the debuff up all the time. It is likely overkill to slot it everywhere, though.
That holds for single target powers. For AoEs, it's a bit more complicated. The proc will roll separately for each enemy, so roughly one in 5 will be hit. However, it's not very easy in the thick of battle to tell which ones it hit, so unless you or your teammates are following up with more aoes, the debuff may be wasted. In other words, to best leverage the achilles heel proc in aoes, you need more aoes. Peacebringers do have a good deal of usable AoEs, but a lot of them come with annoying knockback that makes them difficult to chain up. However, if slotted in the AoEs that *don't* do knockback (nova cone, human cone, dwarf stomp), you could provide a small bonus for your teammates.
Whatever attacks you slot them in, don't do it at the expense of getting actual enhancement percentages. It doesn't do you much good to have the proc if the power you slotted it in misses a lot, does less damage than it should, or recharges too slowly due to skimping on actual enhancements. That said, if you can get it in and still keep decent enhancement levels, I'd certainly go for it in an attack or two. It is useful, especially for beating on one tough target like a boss.
@MuonNeutrino
Student, Gamer, Altaholic, and future Astronomer.
This is what it means to be a tank!
hiya folks, I got some question regarding the Achilles Heel: Chance for Resistance Debuff proc:
1. What are the numbers on the proc, how often does it go off, how long does the effect last, how often Can it occur?
2. Does the effect stack with itself on the same target when slotted in multiple attacks?
3. Is slotting it in multiple attacks useful at all? Attacks within a chain? Attacks in separate chains (one for the AoE chain, one for the single target?)?
4. Which are the best powers to slot it in on a Human/Dwarf PB, lvl 37?
5. Anything else you can think of regarding this proc and PBs?
Wavicle, Energy/Energy Blaster, dinged 50 in Issue 4, summer of 2005.
@Wavicle, mostly on the Justice server.