Otherworldly Escort + Amoeboid Changeling + Intruder Alarm + Phantom Train

Otherworldly Escort

Amoeboid Changeling

Intruder Alarm

Phantom Train

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 Phantom Train 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 Phantom Train ability.
6. Repeat.

This clever loop relies on stripping Otherworldly Escort of its native creature types using Amoeboid Changeling so that when Phantom Train sacrifices it, its death trigger sees a non-Spirit hitting the graveyard and brings it right back with charge counters. Every time Otherworldly Escort re-enters the battlefield, the passive untap engine of Intruder Alarm triggers to freshen up your entire board—crucially untapping Amoeboid Changeling and Phantom Train to do it all over again. As this cycle spins endlessly, Phantom Train grows infinitely large by stacking up +1/+1 counters, while your entire team enjoys infinite activation and untapping opportunities.