Help me understand. This set could use an overhaul at first glance.
The heal is anemic and more importantly slow moving unlike other single-target heals from other sets. Could benefit from having a splash AOE mechanic or have the toss sped up a bit.
The way the two main debuffs work is that in order to get a target to have the full debuff, you need to spam the main target and another nearby target with another casting. The AOE splash debuff outside of the main target only get hit with half the debuff you just tossed, and the area of effect for both is only 8 feet. Envenom and Weaken - the end cost is fine and the AOE is fine it's just the weird half-measure part that bugs me, as they seem to have been designed to encourage spamming more than once every mob. Even if you cast it twice, those that aren't directly selected only get two half-debuff effects layered (if they even stack.)
Neuro breath is fine, I kind of wish the breath animation for all breath powers were a little quicker but I have no complaints against this power.
I like Elixir of Life. It adds fun flavor to a rez. No issues.
Antidote is fine. Would be nice as an AOE like Kinetic's but this works fine as is.
Paralytic Poison hold is kind of odd here. It seems to be a clone of Petrifying Gaze in Dark, and both could use some flavor. Perhaps just give it a decent toxic dot?
Poison Trap is ok, I know it's not as great as the Traps version but I can't say anything bad. The endurance drain component is an interesting choice.
Venomous Gas - ok, here is the big one. Nice strong power, good size, end cost makes sense, but outside of the other two debuffs you don't have much to help you survive being in the middle of mobs. Granted, that's not the case with controllers/masterminds using it but defenders and corruptors don't have that luxury. You have a PBAOE that grabs aggro and at the same time have a cone power with a slightly long animation in the same set with no buffs or heals for yourself. The tohit debuff is weaker than direct target Weaken's, and there is a small damage debuff in here, but I still think overall this set kind of works against itself in some ways, and the way the splash debuffs work just means you spend less time doing other non-poison set stuff, or you just attack more often against lightly debuffed targets instead.
It would have been cool to have some DoTs added to a set with this theme.