Vigor + Deathbringer Thoctar + Sawhorn Nemesis

Vigor

Deathbringer Thoctar

Sawhorn Nemesis

How it works

1. Activate Deathbringer Thoctar by removing a +1/+1 counter from it, putting two +1/+1 counters on it due to Vigor.
2. Activate Deathbringer Thoctar by removing a +1/+1 counter from it, dealing 1 damage to any target.
3. Repeat as desired.

This loop is a masterclass in turning a replacement effect into a relentless engine, entirely fueled by Sawhorn Nemesis doubling the damage dealt by Deathbringer Thoctar. When Deathbringer Thoctar removes a +1/+1 counter to ping a permanent controlled by the player chosen by Sawhorn Nemesis, that damage is doubled to 2. Vigor steps in to replace that damage to your own creature, transforming the prevention into two +1/+1 counters instead. This leaves Deathbringer Thoctar with a net gain of counters after feeding its own activation cost, letting you repeat the process to grow your creatures infinitely and burn down the opposition.