***TRIALS RESPONSE***As a rule of thumb, the smaller a deck is the better it performs. With that in mind, looking at your deck I saw something huge with an absolutely disproportionate quanta usage which doesn't excel at stalling or dealing damage fast. So, I felt obliged to cut the deck down to 30 cards while making it faster and ensure it keeps its poisoning theme.
I immediately dispatched of cards such as Nightmare, Phase Shields, a few Quantum Pillars, the Hourglasses and other generally non-poisonous slow cards (Mitosis, Fire Eater, Fire Queen, Miracle). I changed the Mark to Death to account for the amount of quanta used and added some Scorpions and buffs (for the Deathstalkers). Although I planned to leave them all in, I had to take out all the Sundials, as I prefer the Scorpions actually attack. I finished by adding some Creature Control, a shield and a weapon, because those are always good to have.
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4sa 4sa 4sa 4sa 4sa 4vj 4vj 4vj 4vj 4vj 4vj 52o 52o 52u 52u 55q 55q 590 5c8 5c8 5f6 5f6 5i5 5i5 5i5 5i5 5og 5ur 61q 61q 8pk
I would like to note that, although the above deck is likely more or less going to be enough for grinding Elders, a much better Poison deck could be made using only Death and Water. I recommend something like 7 Death Pillars, 3 Mummies, 6 Poison, 6 Chrysaora, 6 Freeze, 2 Arsenics, Mark of Water. Then again, this one is probably more fun and more versatile in some situations, so I wouldn't sell all my card to make that one.