Valkyrie's Call + Intruder Alarm + Amoeboid Changeling + Umbral Collar Zealot

Valkyrie's Call

Intruder Alarm

Amoeboid Changeling

Umbral Collar Zealot

How it works

1. Activate Amoeboid Changeling's second ability by tapping it, causing another nontoken creature you control to lose all creature types until end of turn.
2. Activate Umbral Collar Zealot by sacrificing the creature targeted in step 1.
3. When the creature dies, Valkyrie's Call triggers, returning the creature from your graveyard to the battlefield as a white Angel.
4. When the creature enters the battlefield, Intruder Alarm triggers, untapping all creatures.
5. Resolve the Umbral Collar Zealot ability.
6. Repeat.

This clever loop turns Amoeboid Changeling's identity-stripping ability into a permanent resurrection engine, thanks to Valkyrie's Call transforming your sacrificed creatures into Angels the moment they return. Because Intruder Alarm untaps all creatures whenever anything enters the battlefield, the very act of your fallen minion returning resets Amoeboid Changeling and Umbral Collar Zealot for another round. You can repeat this sacrifice-and-return cycle indefinitely, fueling Umbral Collar Zealot's surveil ability while generating an endless stream of enters-the-battlefield and death triggers.