Xavier Sal, Infested Captain + Basking Broodscale + Intruder Alarm

Xavier Sal, Infested Captain

Basking Broodscale

Intruder Alarm

How it works

1. Activate Xavier Sal's second ability by tapping it and sacrificing any other creature you control, putting a +1/+1 counter on Basking Broodscale
2. Basking Broodscale triggers, creating a 0/1 Eldrazi Spawn creature token.
3. When the Eldrazi Spawn enters the battlefield, Intruder Alarm triggers, untapping all creatures.
4. Repeat.
5. Once you have infinite +1/+1 counters on Basking Broodscale, you may instead use Xavier Sal's first ability to get infinite copies of creature tokens you control.

This crafty loop hinges on using Xavier Sal, Infested Captain to sacrifice a creature and proliferate, which places a +1/+1 counter onto Basking Broodscale. Because Basking Broodscale triggers whenever one or more +1/+1 counters are put on it, it immediately spawns a 0/1 Eldrazi Spawn token, which in turn triggers Intruder Alarm to untap all of your creatures—including Xavier Sal—so you can repeat the process indefinitely. This engine generates infinite sacrifices, death triggers, and mana from the Eldrazi Spawn tokens, and once your board is sufficiently boosted, you can pivot to Xavier Sal's other activated ability to repeatedly populate your tokens and overrun the board.