Craven is in the Champions of Ruin Faerun book, or some-such. Venomfire + the Lesser Rod of Maximize is good. Since the build is so RAW fuzzy, anyways, might as well go for broke.
Use Extra Spell to get into a single level of Sacred Exorcist. Then use DMM: Persistant Spell on your Druid goodies (Sirine's Grace, for example). And stack those Nightsticks for Bite of the Werebear and that Form of the [landshark] spell. Nothing like having a 43 Str all day long. Might as well add Nymph's Kiss and Touch of Golden Ice. Don't forget to put Improved Unarmed Strike on yourself and that fleshraker: you want to add iterative attacks on top of your natural attacks, particularly after pouncing. If that's too much, just use all that on your animal companion, and use your rod of maximize spell with Control Winds (while under a Control Weather) to have maximized tornado kill everyone (well, 30 damage per round over 10 rounds... plus falling damage... whatever). Persist Stormlord (or whatever, SpC spell), and call yourself "Stormy", while flying around; make sure to share that last one with your Dire Polar Bear. But why stop there? Hire a spellcaster to make an eternal wand of Persistant Wraithstrike and Heroics (Power Attack), and crossclass UMD a bit. Might as well use Divine Power and Righteous Might, too. These are all things I did with my Druid when the DM forced casters to multiclass (one level of Cleric + the Planning and Undeath domains, the fool). The DM was passing out Epic items to the other party members like crazy to help them keep up. I'll never play a Druid again.
Honestly, I don't think advancing the size really matters if you're already using a fleshraker.