The Maker - Incredibly easy, you'd forget that he is a heroic boss. The only thing of note is his Mind Control, and some poison. He hasn't got much health, doesn't do much damage, and is a nice starter for any time, any place.
Broggok - Hah, thought you could sit back and relax in this nice little Furnace? No way, José! This boss, after switching the switch, spawns four waves of orcs. These orcs are quite hardhitting, so try to CC as much as possible. Watch out, though - the elites are usually less hard than the non-elites, so you might want to get the non-elites first. When these waves are defeated, Broggok himself comes, but he isn't too hard - just move out of the poison cloud he makes every once in a while. NOTE: Currently, this can be bugged when you stand too close to the cages when they open. Keep in the middle of the room.
Keli'dan the Breaker - Easy guy after these hard felguards. Note that around his room, there are glowing holes with shards of something above them. If you stand in there, you get a very nice buff, so go and stand there when fighting. As for the fight, it starts off with five casters, which are quickly killed. After that, Keli'dan will break free. He hasn't got much interesting attacks except when he says "Closer.. come closer.. and BURN!" at which points he drags everyone to him and he does some very hard hitting AOE when you're not quick enough, á la Shade of Aran's Arcane Explosion.