Otherworldly Escort + Amoeboid Changeling + Thornbite Staff + Phantom Train

Otherworldly Escort

Amoeboid Changeling

Thornbite Staff

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 and Amoeboid Changeling trigger.
4. Resolve the Amoeboid Changeling trigger, untapping it.
5. Resolve the Otherworldly Escort trigger, returning itself from your graveyard to the battlefield as a Spirit Detective.
6. Resolve the Phantom Train ability.
7. Repeat.

This clever loop turns the self-recurring nature of Otherworldly Escort into an infinite engine by stripping away its native creature types with Amoeboid Changeling so that its death trigger successfully resets it every time. When Phantom Train sacrifices the Escort, it not only feeds its own growth with +1/+1 counters but also sends the Escort to the graveyard, bypassing its built-in restriction against triggering if it's already a Spirit. To tie the whole machinery together, Thornbite Staff equips to the Changeling, allowing its taps and untaps to keep pace with the frantic cycle of sacrifices and returns.