Midnight Guard has at least one +1/+1 counter on it.
Midnight Guard does not have summoning sickness.
You control at least one additional nonlegendary creature.
Mana Needed
({1} magic symbol) available.
Steps
Activate
Midnight Guard using
The Jolly Balloon Man's ability by paying ({1} magic symbol) and tapping it, creating a token copy of another nonlegendary creature you control that is a 1/1 Balloon with flying and haste in addition to its other types.
When the creature token enters the battlefield,
Midnight Guard and
Mana Echoes trigger.
Resolve the
Midnight Guard trigger, untapping it.
Resolve the
Mana Echoes trigger, adding ({C} magic symbol) for each creature you control that shares a creature type with the creature token.
Repeat.
Results
Infinite LTB.
Infinite ETB.
Infinite sacrifice triggers.
Infinite death triggers.
Infinite colorless mana.
Infinite creature tokens with haste.
Infinite token copies of each creature you control with haste except