Casey Jones, Back Alley Brute, and Ob Nixilis, Captive Kingpin

Prerequisites

• Casey Jones, Back Alley Brute on the battlefield
• Ob Nixilis, Captive Kingpin on the battlefield

Steps

1. Declare Casey as an attacker, triggering its first ability, putting a +1/+1 counter on it
2. Casey's second ability triggers, dealing 1 damage to an opponent
3. Ob Nixilis triggers, putting a +1/+1 counter on it and exiling the top card of your library with the ability to play it until your end step
4. Repeat from step 2

Results

• Exile your library with the ability to play the exiled cards until end of turn
• Infinite +1/+1 counters on a creature
• Infinite damage