I get the intention behind dramatically reducing the damage on the targets you chose to directly attack. The idea is to increase damage overall by having it spread out. The problem is that the "benefit" of Vengeful Quills is simply the minor extra damage added by the main quills. You also get to spread poison a bit more. While I'm not one to complain about minor benefits, I do take issue when the main use of quills is basically axed. Before I "upgraded" to this "ultimate", I could use quills to inflict drastic damage against a single target. Giant Lichen Colonies. Vanaduke. Lumbers. That sort of thing. I have no control over where my actually damaging quills end up anymore.

I'm cool with the sacrifice of this tradeoff. It makes Vengeful Quills and advanced skill. However, the payoff is nonexistent, and as such Vengeful Quills is but a nerf. I have a simple proposition to make Vengeful worth it:

Each Vengeful Quill, when broken, will spawn two Caustic Quills at random enemies, instead of just one.

Bam! Badabing! Tradeoff now worth it!

You could also actually make the ability as awesome as it sounds and let Vengeful Quills spawn even more Vengeful Quills but I know how much you guys hate fun mechanics. If it let me spread quills around for as long as I could keep hitting quilled enemies, the 70% reduction in damage would be worth it.