Mikaeus, the Unhallowed + Cryptic Trilobite + Crovax, Ascendant Hero
Infinite colorless mana that can only be spent to activate abilities, Infinite death triggers, Infinite ETB, Infinite LTB
Activate Cryptic Trilobite by removing a +1/+1 counter from it, adding that can only be spent to activate abilities.
Repeat step 1 until Cryptic Trilobite does not have any +1/+1 counters on it.
Cryptic Trilobite dies as a state-based action due to having 0 toughness.
Cryptic Trilobite's undying ability triggers, returning it from your graveyard to the battlefield with a +1/+1 counter on it.
Repeat.
Component Cards
How It Works
Activate Cryptic Trilobite by removing a +1/+1 counter from it, adding that can only be spent to activate abilities.
Repeat step 1 until Cryptic Trilobite does not have any +1/+1 counters on it.
Cryptic Trilobite dies as a state-based action due to having 0 toughness.
Cryptic Trilobite's undying ability triggers, returning it from your graveyard to the battlefield with a +1/+1 counter on it.
Repeat.