Infinite creature tokensInfinite creature ETBInfinite mana creatures you control can produceInfinite untap of creatures
How it works
Activate Xavier Sal's first ability by removing a counter from a permanent you control, creating a copy of a creature token you control that enters the battlefield with at least one +1/+1 counter on it due to Arwen.
When the creature token enters the battlefield, Intruder Alarm triggers, untapping all creatures.