Derevi, Empyrial Tactician + Cauldron of Souls + Aerith Gainsborough + Bloodflow Connoisseur

Prerequisites

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Steps

1. 1Activate Cauldron of Souls by tapping it, giving Derevi and Aerith persist until end of turn.
2. 2Activate Bloodflow Connoisseur by sacrificing Derevi.
3. 3When Derevi dies, its persist ability triggers, returning it from your graveyard to the battlefield with a -1/-1 counter on it.
4. 4When Derevi enters the battlefield, it triggers, untapping Cauldron of Souls.
5. 5Activate Bloodflow Connoisseur by sacrificing Aerith.
6. 6When Aerith dies, it triggers twice.
7. 7Resolve Aerith's persist trigger, returning it from your graveyard to the battlefield with a -1/-1 counter on it.
8. 8Resolve the second Aerith trigger, putting a +1/+1 counter on each legendary creature you control, thus removing the -1/-1 counters from Aerith and Derevi.
9. 9Resolve the Bloodflow Connoisseur abilities from steps 2 and 5.
10. 10Repeat.

Effects

• Infinite +1/+1 counters on a creature
• Infinite +1/+1 counters on legendary creatures you control
• Infinite creature ETB
• Infinite creature LTB
• Infinite creature sacrifice triggers
• Infinite death triggers