Otherworldly Escort + Amoeboid Changeling + Intruder Alarm + Viscera Seer

Otherworldly Escort

Amoeboid Changeling

Intruder Alarm

Viscera Seer

How it works

1. Activate Amoeboid Changeling's second ability by tapping it, causing Otherworldly Escort to lose all creature types until end of turn.
2. Activate Viscera Seer by sacrificing Otherworldly Escort.
3. When Otherworldly Escort dies, it triggers, returning itself from your graveyard to the battlefield as a Spirit Detective.
4. When Otherworldly Escort enters, Intruder Alarm triggers, untapping all creatures.
5. Resolve the Viscera Seer ability.
6. Repeat.

This elegant loop turns Otherworldly Escort into an immortal sacrifice engine by exploiting its specific dying trigger. Because Otherworldly Escort checks whether it's a Spirit when it dies, stripping away its creature types with Amoeboid Changeling ensures it never qualifies as a Spirit, allowing its revival ability to trigger indefinitely. Viscera Seer acts as the necessary outlet to bin the creature for scry depth, while Intruder Alarm uses the resulting entry triggers to untap your entire board—including Amoeboid Changeling and any mana-producing creatures you control—readying the whole setup to repeat the cycle ad infinitum.