Subtraction (25 player)

This achievement requires you have 20 people that:
-Can do polarity Shift
-Do extremely good DPS to beat the enrage timer.

Just to give an idea of how hard this achievement is, when we 25 man him, we just barely beat the enrage.

This is actually quite an easy achievement if people can watch both their cooldowns and the polarity changes. It's also very gear dependant. I didn't really pay much attention but we did it with 2 healers I think and 2 tanks, rest was dps specced and equipped (yes we actually made the excessive healers go and respec). After a few wipes where people got carried away in their cooldowns, failing to do the jump and getting disconnected or lagged due to the huge fps drop, we made it. Also, popping 2 heroism/bloodlusts should do the trick. Pop one after the first polarity shift, and the second one

We did it last night with 2 tanks and 3 healers and some bringing their mains and dps alts. We downed him after he took out half the raid by enraging. The wipes before where on silly mistakes but the main priority here is to not die!