One thing that should help is to obtain the Ring of Skies, from the Ghost Tower. Once you reach the left side of the bottom level in that area (mind the weapon-stealing ghosts), go into the room left; you'll need to platform across over a set of insta-kill spikes, and the room is full of bats. (Heat Aura helps.) You'll need to break a few barrels to reveal the ring box, but the Ring of Skies will boost your jump distance, enough to make the platforming during the final segments, while not easy, it'll be less frustrating.
As for weapons/skills, Meltroth makes short work out of everything except the Treants/Ents. When faced with many enemies, have Gatchan out, or repeatedly cast Sleep. (If you were diligent in questing, you've got it, if not, find the Spirit Box in the Library and do its quest. Golden essence, 2 per cast. Don't have Gatchan? You can find him behind a door in the halls that takes you to a even-more-retro platforming challenge.)
Once you reach Corvax, back up, make sure Harnakon's counter isn't ticking down, take all the buffs you've got with your best weapon, and get in there. If you have an Arcane Immunity scroll, use it as well, that will make things a lot easier. (Didn't have one myself, so I just offensive buffed and wailed away.) Corvax doesn't have that much health, really, he/she is just a teleport-spamming glass cannon, but the platforms block the mage's bolts. (Yeah, I think Corvax is a she, though, due to the fact that that mage wears pink.)
On defense, Ice Blocks are usually a good distraction for most waves, and the Skeleton Warriors, though the latter die easily. Red and Green Armors are more durable, but you'll want to save Harkanon's green essence to summon Goblin Healers first. (100 green essence! Geez!) Repeated casting of Cloud of Death will quickly kill Elven Mages and Archers (one shot!), Warriors (two shots) The Treants/Ents are a lot more difficult, but with Skeleton Warriors running interference, your Armors should be able to handle them. Skeleton Archers and Mages should be perched on the ledges to provide ranged support against everything; and the Gryphons/Harpies, whichever you want to call them, die quickly to Cloud of Death, cast from a ledge.
Under no circumstances should you touch your own CoD, though. It hurts, a lot.
Post edited June 25, 2013 by rabidchoco