Originally Posted by
mascaron
If the adds aren't dying, then he's 100% guaranteed letting them get hit by the shadowblaze, the breath, and/or letting them touch a fire. Any of those can easily cause him to die a horrible death.
What we do is tank nef in the center of the room and have the add tank kite adds around the outside of the room in a circular fashion. With boss timers for the blaze (as well as the actual animation of the ball shooting out from nef) it's not too hard for him to shift as soon as it comes out to prevent the adds from getting hit by it, and then he runs out of range of fire. If he's going to stun the adds, he waits for the blaze to hit and he's sufficiently far enough away that a stun won't be so long that a fire might work its way into hitting an add. As add tank is moving around the room, Nef tank needs to rotate boss so that add tank is always to the side of Nef. This way add tank will never be hit by breath or tail swipe. This forces some raid movement, but it really hasn't been an issue for our guild.
Also, on normal mode in both 10 and 25 we push 3 crackles in p1, 0 in p2. We start p3 around 61-62% on Nef and push the next crackle shortly after the raid gathers on the ground. If you're interested in doing 3 crackles p1, it's rather simple if you time it correctly. Have 1 dps in charge of lowering Onyxia from ~7% (when we stop refreshing dots) to ~150k hp (or lower if they feel comfortable knowing they won't kill). As soon as raid warning for 5 seconds until electrocute comes up, finish off Onyxia. Ideally crackle hits 1-2 seconds after Ony dies, giving ample time for healers to get the raid up while you run to platforms.