Aggravated Assault, Bear Umbra, and Pako, Arcane Retriever

Prerequisites

• Aggravated Assault on the battlefield
• Bear Umbra on the battlefield
• Pako, Arcane Retriever on the battlefield
• Bear Umbra attached to Pako
• You control lands that can tap to produce at least
• An opponent is unable to block and kill creatures you control

Steps

1. Declare Pako as attacker
2. Pako and Bear Umbra triggers
3. Resolve the Pako triggers, exiling the top card of each player's library and putting a fetch counter on each of them, putting a +1/+1 counter on Pako for each noncreature card exiled this way
4. Resolve the Bear Umbra triggers, untapping all lands you control
5. Proceed to your next main phase
6. Activate Aggravated Assault by paying , untapping all creatures you control and getting an additional combat and main phase after this one
7. Repeat

Results

• Infinite combat phases
• Infinitely large Pako