What is the most damaging Wizard spell to a single target?

Question

What is the most damaging Wizard spell to a single target?

Or well, it can accidently hit others as well but the mainpoint is; if I don't care about cost and I want to do the most damage possible to a single target; what spell should I use?

Answer 1

If you consider uncontrolled spells as well, then runed Arcane Torrent with Arcane Dynamo gives 11x the base damage: see the first answer in What abilities will consume the Arcane Dynamo stacks? and its linked spreadsheet.

Answer 2

Disintegrate with Chaos Nexus does 155% damage in a beam, but shoots out little beams for 40% to targets close to you. The 155% damage effect and the 40% damage effect can hit the same target, which means you are creeping towards 195% damage if you are close.

It's very versatile and I've used it a lot on my hardcore wizard, where you need a lot of defensive spells and thus have to be able to deal with a large amount of circumstances with a small amount of offensive spells.