Posix, Pandaren Priest on Darkmoon Faire.
Unfortunately penance only gives ONE (1) stack per tick of the penance no matter what amount of stacks the soaker has. It will always give 3 stacks, never more. At the begging of a fight your best bet is to PI/hero and just use flash heals. The PW:S Glyph will also give you stacks, so use that at the very end before your spriest's 25 stacks disappear.
The fight is very easy with 2 healers that are competent. We do it every week with disc/rdruid. Although with the nerfs that just hit im sure the dps requirements are not nearly as high from each players as they once were.
The way decimation works is dealing the larger of its base damage or 90% of the tanks health. (Not sure what it is after the nerfs, but its a big hit, regardless) It cannot be resisted or blocked, but it can be parried/dodged/absorbed. Disc shields are amazing for this as they can soak huge chunks of the attack.
The real trick is making sure you get a buffed shield on the tank rather than a normal one. You'll need to throw one direct heal before you shield to ensure you have Vital Flame up to affect the shield. If you shield first, you'll swap buffs from spark to flame, but the shield itself will still sit in the unbuffed 20-30k range.
I was so sure you were wrong I went and browsed our logs. Turns out, I'm wrong. According to the logs you do only get one stack per Penance tick regardless of Torment stacks. Good to know, it's something I hadn't picked up in the past.
A log segment for anyone who is interested:
Code:[23:45:58.207] Posix casts Penance [23:45:58.624] Posix Penance Abominatus +11936 [23:45:58.826] Posix casts Penance [23:45:58.988] Posix gains Vital Spark (76) from Posix [23:45:59.046] Posix Penance Abominatus +11600 [23:45:59.466] Posix gains Vital Spark (77) from Posix [23:45:59.544] Posix casts Penance [23:45:59.875] Posix Penance Abominatus +10266 (O: 1391) [23:46:00.230] Posix gains Vital Spark (78) from Posix [23:46:00.230] Posix gains Vital Spark (81) from Posix [23:46:00.539] Posix begins to cast Flash Heal [23:46:01.556] Posix begins to cast Flash Heal [23:46:01.604] Posix Flash Heal Abominatus +30720 [23:46:01.899] Posix gains Vital Spark (85) from Posix [23:46:02.543] Posix begins to cast Flash Heal [23:46:02.711] Posix Flash Heal Abominatus +30482 [23:46:03.126] Posix gains Vital Spark (89) from Posix [23:46:03.616] Posix begins to cast Flash Heal [23:46:03.912] Posix Flash Heal Abominatus +31724 [23:46:04.286] Posix gains Vital Spark (93) from Posix
Taken from this query on this log.
Posix, Pandaren Priest on Darkmoon Faire.
Penance used to give as many stacks per tick as other heals did but it was fixed very early, that's probably why you thought it still did. Normally if you check something and there's no hotfix notes you'll assume it still works the same way unless you're getting problems because of it.
Yeah, I imagine that's why I have found it harder to get into the 120+ stacks range of late.
Posix, Pandaren Priest on Darkmoon Faire.