Missy + Skirk Alarmist + Intruder Alarm + Ashnod's Altar

Missy

Skirk Alarmist

Intruder Alarm

Ashnod's Altar

How it works

1. Activate Ashnod's Altar by sacrificing another nontoken nonartifact creature, adding CC.
2. When the creature dies, Missy's first ability triggers, returning the creature from your graveyard to the battlefield face down as a 2/2 Cyberman artifact creature.
3. When the creature enters the battlefield, Intruder Alarm triggers, untapping all creatures.
4. Activate Skirk Alarmist by tapping it, turning the creature face up.
5. Repeat.

This loop turns the cycle of life and death into an engine for infinite mana and triggers, utilizing Missy to continually resurrect your fallen nonartifact creatures as face-down 2/2 Cyberman artifact creatures whenever they hit the graveyard. Ashnod's Altar provides the sacrifice outlet to generate colorless mana while feeding them right back into Missy's ability. Every time that fresh Cyberman enters the battlefield, Intruder Alarm triggers to untap all creatures, ensuring Skirk Alarmist is immediately ready to tap and flip that creature face up—overriding the end-step sacrifice clause by resetting its state.