Heroic: Cho'gall

Defeating Cho'gall on this difficulty causes the floor to collapse, revealing the optional boss, Sinestra.

There are a few marked changes in this encounter vs. its normal counterpart. I'll do my best to break them down by factors you'll have to deal with individually. First and foremost Cho'gall has significantly more HP than in normal so your raid dps will need to be quite high to defeat this encounter.

Probably the most important change you'll encounter first is the change to [spell=93366]. Rather than giving Cho'gall a stacking 10% damage buff for 20 seconds increasing every 3 seconds you Worship, it will now give Cho'gall a 5% damage buff that lasts one minute. Since he will cast [spell=93204] at roughly the same rate of every 20 seconds, it becomes crucial to interrupt all mind controls before any stacks are applied as you may quickly become overwhelmed by not being able to drop the Worship stacks.

The next major change is the elementals he summons throughout phase 1. Rather than do nothing but get absorbed into his weapon as in normal, they will be attackable for approximately 10 seconds before getting absorbed. It is important to bring them to 1 HP as for every 10% of their health remaining, Cho'gall will do 5% more damage from their effect (direct fire damage to tank from fire elemental, raid shadow pulse from shadow elemental).

There are two corrupted adherents spawning at a time in 25-heroic (still only one in 10-heroic), but their increased health and that of the spawned blood means you will need to be dropping these in roughly the same location as to be able to destroy the bloods as efficiently as possible. If you're meeting the DPS requirement you should be pushing phase 2 just before or after the 5th set of adherents spawns.

Phase 2 is primarily made more difficult by the increased health to burn through while the entire raids corruption bar slowly ticks upward. However, to further complicate matters, [npc=50265]s will spawn roughly every 25-30 seconds close to Cho'gall. These cannot be effectively killed and the entire raid must be careful to avoid them, as while they only melee they hit for significant damage.

At 2% Cho'gall will begin staggering toward the trapdoor in the middle of the room. He will only die when he has reached it, falling on it and causing it to break. You can avoid a low-% wipe by keeping him close to the trapdoor when he reaches 5% or so, as you will not need to wait for him to move and ending the fight that much earlier. His body can be located for looting below in the Twilight Caverns.

We managed to finish the glory today. (Heroic Cho'gall is bugged right now...)

I came with friend in party, we pulled boss with taunt to the middle of the room (killed all the adds before pull), then after few seconds nuked him to 0%, he then revived to full HP and bugged, we waited like 10-15s, my friend who taunted and pulled the boss used shadowmeld, then moved a little a bit and then hearthstoned. After he disappeared I waited for few seconds, boss got into the middle, died and I got the achievement. Worked twice in the row.