When Anti-Venom enters, if he was cast, return target creature card from your graveyard to the battlefield.
If damage would be dealt to Anti-Venom, prevent that damage and put that many +1/+1 counters on him.
Anti-Venom is a mono-white reanimator/voltron hybrid: cast him to drag your biggest creature back from the graveyard, then turn him into an unkillable beater since all damage dealt to him becomes permanent +1/+1 counters. Early turns you fill the yard and ramp, then deploy Anti-Venom to recur a bomb and start swinging while he grows from every block and burn spell aimed at him.
Built-in reanimation on a body the moment you cast him
Damage prevention makes him near-impossible to kill in combat or with burn, and he snowballs from every attempt
Mono-white gives access to the format's best protection, wraths, and recursion
Blink/sacrifice loops can repeat the reanimation trigger every turn
Reanimation only triggers when 'cast,' so commander-tax recasts and blinks reset value but exile/-X/X effects shut him off
Mono-white struggles with raw card advantage and big-mana ramp compared to other colors
Vulnerable to exile, bounce, and -X/-X effects that bypass damage prevention
Needs setup to fill the graveyard with worthwhile targets before he comes down
Doubles as another reanimation body that pairs with sac/blink loops to recur your bombs.
Add efficient self-mill or discard outlets (Faithless-style white digging, Buried Alive, Entomb effects in mono-W are limited so lean on Stitcher's Supplier alternatives and cycling) plus reliable blink (Restoration Angel, Eldrazi Displacer) to abuse the cast trigger. Upgrade the equipment package with the full Sword suite and Lightning Greaves for protection, and include white's best tutors like Enlightened Tutor and Steelshaper's Gift to assemble your voltron plan faster. Round out with strong reanimation targets that win on their own to make each ETB matter.