Myrkul, Lord of Bones, and Barrenton Medic

Prerequisites

• Myrkul, Lord of Bones on the battlefield
• Barrenton Medic on the battlefield

Steps

1. Activate Barrenton Medic's second ability by putting a -1/-1 counter on it, untapping it
2. Repeat step 1 until Barrenton Medic dies as a state-based action due to having zero or less toughness
3. Myrkul triggers, causing you to exile Barrenton Medic and create a token copy of Barrenton Medic that is an enchantment and loses all other card types
4. Whenever damage would be dealt to you or a permanent you control, activate the Barrenton Medic token's first ability by tapping it, preventing one damage to you or that permanent
5. Activate the Barrenton Medic token's second ability by putting a -1/-1 counter on it, untapping it
6. Repeat from step 4 as necessary

Results

• Prevent all damage that would be dealt to permanents you control
• Prevent all damage that would be dealt to you