I like
Swarm of Crystals. The downside? 15' cone means you're way too close, and for big stuff you'll actually have to close past their natural reach to hit. The upside? You don't need line of sight, you don't need to make a touch attack, no save, no SR, irresistible damage (not an energy, DR won't stop a spell even if it's slashing), goes up 1 die for each power point. It may only be d4's, but it's one of the best "shut up and take it" effects I've seen.
Other than that, you've got the right of it. The Wilder is a blaster, that's pretty much all it's allowed to be. Grab a variety of blasting methods, a couple of non-blasty powers just in case, and sink everything else into keeping yourself alive.