I have been running a Poison/Sonic build over on everlasting
ST wise you can melt just about anything with the stacking -res
The fact that you can skip a lot of the primary and not miss many doses allow for some handy utilities
Here is my 2 cents on all the poison powers at least for defenders
Alkaloid- So it's a single target heal that's going to give about 230 ish hp at 50 unenhanced, not bad but it's slow really slow... It also grants 20% res to toxic so you can buff that tank when fighting zombies in the low levels. skip it at the start, take it when you have nothing else to grab its only Okay
Envenom- Now this is the good stuff, -50% def all types -60% Res -50% Regen and it reduces heals on target as well, this thing is nasty. Small splash effect means the best use is going to be having a tank gather targets first or corner pull to maximize targets hit. Did I mention it recharges in 12s unenhanced and lasts 30s. You take this power as soon as you can first thing its the Best you get Period
Weaken- your other Good debuff -28% tohit debuff -37% dam and it guts the targets power effects by 74% so heals holds imobs, buffs debuffs, all of it gutted. Sam small splash as above, however, this power has a longer recharge of 16s
Neurotoxic Breath- so -81% recharge sounds really good, and it's stronger than frost breath and almost the same as infrigidate from cold domination, except this, is a cone. the issue is it does nothing for that alpha strike. this power gets a bad stigma due to -recharge being the kind of power that only shines in drawn-out combat. take it if you can its handy but not game changing like the last two debuffs
Elixir of Life- This is basically mutation, the "crash" is problematic on a target that already face planted a few mins ago and it could actually cause them to crash out again due to end loss at bad times but its not super hard hitting but a bit of a surprise. the 50% dmg buff is nice and the +Rech 100% is nothing anyone is going to complain about 90s later the throw-up and are sudo held.
Antidote- its basically clear mind with some toxic res buf thrown on for flavor if you would take clear mind take ikt but its not a thing to ever slot
Paralytic Poison- one of the worst ST holds iv ever used, 11s mag 3 hold 16s recharge so you cant stack it with itself unenhanced, it deals no damage (it really should or at the very least a slow effect as its supposed to paralyze the target) has no debuff associated with it no slow effect no - reach SKIP, unless you have another hold to combo with its not worth the slots or the power.
Poison Trap- 31 ticks of 2 toxic dmg and a AoE hold...in trap form so you need to drop this and get a mob to walk on it or AoE near it. once it pops it active for a long time 260s and you can drop that nasty mine in 1.1 seconds. completely stops end recover on all targets (not really useful as end recover stoping will almost NEVER come in to play with normal spawns) it can apply 2 mag3 holds but then the suck starts. 2% chance of having the holds stack. 1 of the mag 3 holds applies every time the other only has a tiny chance to proc and that second hold only lasts 4s so stopping boss is a maybe at best. if you take it slap the chance for mag 2 hold from GW set in it. it could be slotted with a Ton of procs as it takes hold and damage sets but i have not tested to see if that's worth it or how often it proc it is a spawned pet causing the effect and they act ...odd with procs
Venomous Gas- So on a MM this is great, plop it on a pet and they run into melee -25% res on target they are kicking in the face Great.
on a defender, its on you to walk into melee to apply that -25% Res -12% Def and -12% tohitdebuff (again unenhanced) This power will kill you, but it is useful. stacking this with your other -res will stack to 85% and that's A lot of damage potential