But any constructive criticism, without changing the basic character of the deck, is welcome.
Well the thing is, the "basic character of the deck" isn't efficient at all.
Forty-six cards with no hourglasses is just too much. Many cards only have one copy, so there's no guarantee you'll draw anything in time. There isn't any overall strategy either.
But if it can poison your opponent, it's in there. And it does okay against AI3.
Exactly, and a punch of poisonous cards thrown together isn't going to do "okay" against anything higher than AI3.
There are many unupgraded decks that will quickly and consistently beat AI3, some of them having a good chance of elemental mastery.
You have 29 upgraded cards, so you could sell some of those and putting together a Top50 farmer or even try killing some false gods.
If it's really the poison you want, I'd suggest using either a classic water/death poison speed deck or some of the new scorpion decks. Using everything is just going to be too bulky.