This is really easy, even though they took away the last shrine, there is still a shrine buy the giant boss that summons the undead. If you look where the kobolds spawn near him is the cave, go inside, and pull the first few Mephits to the stairs. Once they are killed you can go left if your careful and rest without aggroing the room full of Mino's and trolls.
Once your rested (and you have all the 4 shards) go to the boss portal, and hop in. Have 1 character run to boss ( have cleric put fire protection on him) and run him around the pillars while the rest of the party proceeds to go inside each of the elemental rooms and kill the mobs inside. For every room you clear, you take away one of the Fire giants buffs. Once each room is cleared, still have a runner runing the giant around in circles, while you range/Magic missile/web/or command if your wis is high enough. If a someone else besides the runner aggro's him, have the runner hit him a few times to get agro back/or taunt. This works best when coordinating the team with voice. With a good runner, and cleric, he'll be dead in seconds.
When fighting him on hard, or elite, make sure you bring lots and lots of fire protection potions, as rebuffing everyone tends to deplete spellpoints really fast.
I hope this can be of some use.
If anyone wants, I can write an in depth guide from start to finish and post some screenshots.
*edit*
didnt even realize that i made this for the Stormcleave boss...hehe..need sleep...
