Fain, the Broker, Thornbite Staff, Arcane Adaptation, and Xathrid Necromancer

Prerequisites

• Fain, the Broker on the battlefield
• Thornbite Staff on the battlefield
• Arcane Adaptation on the battlefield
• Xathrid Necromancer on the battlefield
• You control at least one additional creature
• Thornbite Staff attached to Fain
• Fain does not have summoning sickness
• "Human" chosen with Arcane Adaptation

Steps

1. Activate Fain's first ability by tapping it and sacrificing a creature
2. When the creature dies, Xathrid Necromancer and Fain trigger
3. Resolve the Xathrid Necromancer trigger, creating a 2/2 Zombie creature token
4. Resolve the Fain trigger, untapping it
5. Resolve the Fain ability from step 1, putting two +1/+1 counters on a creature you control
6. Repeat

Results

• Infinite +1/+1 counters
• Infinite death triggers
• Infinite ETB
• Infinite LTB
• Infinite sacrifice triggers