Activate Viscera Seer by sacrificing Otherworldly Escort.
When Otherworldly Escort dies, it triggers, returning itself from your graveyard to the battlefield as a Spirit Detective.
Resolve the Viscera Seer ability.
Activate Viscera Seer by sacrificing Otherworldly Escort.
When Otherworldly Escort dies, its undying ability triggers, returning it from your graveyard to the battlefield with a +1/+1 counter on it.
Resolve the Viscera Seer ability.
Repeat.

Infinite LTB

Infinite ETB

Infinite sacrifice triggers

Infinite death triggers

Infinite scry 1

Mikaeus, the Unhallowed

Otherworldly Escort

Viscera Seer

Activate Amoeboid Changeling's second ability by tapping it, causing Otherworldly Escort to lose all creature types until end of turn.
Activate Phyrexian Altar by sacrificing Otherworldly Escort.
When Otherworldly Escort dies, it and Amoeboid Changeling trigger.
Resolve the Amoeboid Changeling trigger, untapping it.
Resolve the Otherworldly Escort trigger, returning itself from your graveyard to the battlefield as a Spirit Detective.
Repeat.

Infinite colored mana

Amoeboid Changeling

Thornbite Staff

Phyrexian Altar

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

Infinite mana creatures you control can produce

Infinite untap of all creatures

Intruder Alarm

Combos with "Otherworldly Escort"