Midnight Guard, and Splinter Twin

Prerequisites

• Midnight Guard on the battlefield
• Splinter Twin on the battlefield
• Midnight Guard does not have summoning sickness
• Splinter Twin attached to Midnight Guard

Steps

1. Activate Midnight Guards ability with Splinter Twin to create a copy of itself
2. When the token enters the battlefield Midnight Guard will trigger untapping itself
3. Repeat

Results

• Infinite ETB
• Infinite hasty tokens