Originally Posted by
kissmonster
Some things I've learned. If he tries to cast Cata before going in to the first imp phase, it ALWAYS fails(you don't have to interrupt this).
Knowing this, you can use the damage buff from his stun to time with your chaos bolt attacks. Instead of using Dark Soul right at the start, save it until right after you you get the pet. You should have 3 embers at this point. Start casting Chaos Bolt, and as soon as it is about to go off charge-stun him. Cast your other two chaos bolts and if you did it right you can get all 3 chaos bolts to get the 100% damage buff. Trying to time my chaos bolts with stun has allowed me to get him down to 56% by start of the first felhunter phase.(it's at this point where everything goes to hell for me, so I still haven't killed him). I'm ilvl 491 currently.
Another good thing to know. Gateway jumping to put the gateway debuff on you allows you to go more than a minute(or more if you are good at timing it), without getting ANY spells cast on you. He might get one or two dots when he transitions to summon imps, but that is it. So instead of putting the gateway into an LoS location, I put it on the side of the main circle area so I'm always in range of him while jumping back and forth on the gate.
If anyone has good tips on the felhunter phase, this is really what is standing between me and victory. >.<. The strat that has worked for me(sometimes) is pre-casting Sac to get a shield up, charge stunning the first one and one-shotting it with chaos bolt, fearing/casting havok on the second, then using chaos bolt and hoping to kill the last two. It's pretty rare I get past this phase though.