Basically find the artifact macguffins, put them together into one big artifact and thwart the baddies.
"Thousands of years ago, the Valaes Tairn elves came to Khorvaire. By combining four elven magic items into one, their priests created a potent headpiece with power over ancestral spirits and death."
There are a few creatures that exist in 3.5 like an Imp and Kruthiks but there are some new ones as well.
Deathgaunt Madcaster, Level 6 Controller
Deathgaunt Lasher, Level 5 Soldier
Deathgaunt Spiner, Level 4 Artillery
Deathgaunt Drover, Level 4 Skirmisher
Deathgaunt Hordeling, Level 4 Minion
Dreaddaw Darkliege, Level 4 Controller
Dreaddaw Reaver, Level 4 Skirmisher
After that, it's stuff in the 4e Eberron setting book and NPCs I'll have to remake from scratch.