Otherworldly Escort + Amoeboid Changeling + Intruder Alarm + Yahenni, Undying Partisan

Otherworldly Escort

Amoeboid Changeling

Intruder Alarm

Yahenni, Undying Partisan

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 Yahenni 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 Yahenni ability.
6. Repeat.

By using Amoeboid Changeling to strip away Otherworldly Escort's creature types, you bypass its safeguard against coming back as a Spirit, allowing its death trigger to constantly resurrect it. When Otherworldly Escort re-enters the battlefield, Intruder Alarm untaps all your creatures—including the Changeling and any mana producers you might have—while Yahenni, Undying Partisan stands ready as the reliable sacrifice outlet to feed this endless loop.