Felidar Guardian + Mercurial Pretender

Prerequisites

• You have enough mana to cast Mercurial Pretender.

Steps

1. 1Cast Mercurial Pretender by paying its mana cost, choosing to have it enter the battlefield as a copy of Felidar Guardian
2. 2When Mercurial Pretender enters the battlefield, it triggers, blinking Felidar Guardian.
3. 3When Felidar Guardian enters the battlefield, it triggers, blinking Mercurial Pretender. Choose to have Mercurial Pretender enter the battlefield as a copy of Felidar Guardian.
4. 4Repeat from step 2.

Effects

• Infinite creature ETB
• Infinite creature LTB