Whenever damage would be dealt to you, With Great Power... causes that damage to be redirected to Anti-Venom.
Anti-Venom will then prevent the damage and put that many +1/+1 counters on it instead.

Prevent all damage that would be dealt to you

Lock

Anti-Venom, Horrifying Healer

With Great Power . . .

Activate Anti-Venom using Walking Ballista's ability by removing a +1/+1 counter from it, targeting itself and putting two +1/+1 counters on it due to its replacement effect and Lae'zel.
Activate Anti-Venom using Walking Ballista's ability by removing a +1/+1 counter from it, dealing 1 damage to any target.
Repeat.

Infinite damage

Infinite +1/+1 counters on a creature

Agatha's Soul Cauldron

Lae'zel, Vlaakith's Champion

Walking Ballista

Activate Anti-Venom using Walking Ballista's ability by removing a +1/+1 counter from it, targeting itself and putting two +1/+1 counters on it due to its replacement effect and Collective Inferno.
Activate Anti-Venom using Walking Ballista's ability by removing a +1/+1 counter from it, dealing 1 damage to any target.
Repeat.

Collective Inferno

Activate up to five lands by tapping them, adding at least {W}{W}{W}{W}{W}.
Cast Anti-Venom by paying {W}{W}{W}{W}{W}.
When Anti-Venom enters, its first ability and Cloudstone Curio trigger.
Resolve the Cloudstone Curio trigger, returning nothing to your hand.
Resolve the Anti-Venom trigger, returning Peregrine Drake from your graveyard to the battlefield.
When Peregrine Drake enters, it and Cloudstone Curio trigger.
Resolve the Peregrine Drake trigger, untapping up to five lands.
Resolve the Cloudstone Curio trigger, returning Anti-Venom from the battlefield to your hand.
Activate Ashnod's Altar by sacrificing Peregrine Drake.
Repeat.

Combos with "Anti-Venom, Horrifying Healer"