"Until it's in there, just a little MSPaint picture you made yourself should be fine."(Vrt)
Even if you cannot draw, the picture you create is sufficient.
The cost is prohibitively high to use in anything but Mono Death and then even then the creatures aren't cost effective for the Venom ability with Deathstalker + anything. Perhaps 4 or even 3 
for the playing cost, and keep it 2 and 2 for activation. Its got to compete with Deadly Poison and Arsenic too, both which are cheap cards.
Venom with Attack >0 0 is worth +3 quanta cost.
This card adds that ability for 3|2 + (6/number of creatures) quanta.
Pack CC and Graveyard to get Venomed Skeletons.
The important difference between Deadly Poison, Arsenic and Deadly Plant is the rate of poison.
Deadly Poison deals 3T damage
Arsenic deals 4T + T(T+1)/2
Deadly Plant deals T(T+1)(T+2)/6
Deadly Plant catches up with Arsenic at turn 5.
However it is never as cheap as Arsenic it does kill the opponent 3 Turns before Arsenic (if both are played at the same time) and kills FGs 6 turns sooner.
Shields will stop a Boneyard based deck and Graveyards are even slower to play. CC takes ages with Death, multiple Plagues and even a few Plants here is going to set you back massively in quanta and turns that the opponent spends killing you. Even a Cockatrice will survive 5 turns after Plague/Virus and 3 after double poisoning, and that 15 damage is hard to replace. Combined with the fact that poison is more effective in massive numbers and/or over time, and you just created a costly reactive deck that likely will fall to many major archetypes, including but not limited to speed poison and anything with Quint. Flying Arsenics can do much more for much less, sometimes as a Trio with Adrenaline and Heals.
As for creatures to play it on, as it stands Ivory, or really any other Dragons are too expensive to see any benefit to this simply because the opponent has far more to fear from the ten damage than that one incremental damage per attack. Flesh Spiders and Recluses are a good bet, but CC is very dangeorus. Deathstalkers already use this, so no point. Skeletons can be stopped by almost any shield and while Elite Skeletons probably benefit the most from this card, overall they have little impact. Viruses and Retroviruses already have a good use besides this card. Expanding to a Death/Dark duo means likely Darkness creatures, and Minor Vampires and Vampires already have good abilities. Gargoyles are more expensive for a duo and Dragons almost prohibitively so, considering the costs to play effectively. In fact, the creatures best suited for this card would be a Life/Death duo with possibly Scorpions, Thorn Shields, this, and Frogs, possibly Cockatrices too. They provide the most bang for the buck creature wise.
As for the comparison with Arsenic, yes, it might overtake a lone Arsenic in a poison contest. Usually no one runs just a single Arsenic if the goal is to poison someone out. Deadly Poisons or even Adrenalines are used, as well as occasionally Scorpions and Deathstalkers. The 2
cost makes it flexible, which Poisonous/Deadly plant currently is not.
