The Jolly Balloon Man in exile (exiled by Agatha's Soul Cauldron).
All other permanents on the battlefield.
Midnight Guard has at least one +1/+1 counter on it.
Midnight Guard does not have summoning sickness.
Opponents control at least one artifact and/or enchantment.
({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 Dockside Extortionist that is a 1/1 Balloon with flying and haste in addition to its other types.
When the Dockside Extortionist token enters the battlefield, it and Midnight Guard trigger.
Resolve the Dockside Extortionist token's trigger, creating at least one Treasure token.
Resolve the Midnight Guard trigger, untapping it.
Activate a Treasure by tapping and sacrificing it, adding ({1} magic symbol) .
Repeat.
Notes
If opponents control two or more artifacts and/or enchantments, this combo nets infinite Treasure tokens and colored mana. Once you have infinite mana, you may target any other creature using step 1 instead.
Results
Infinite LTB.
Infinite ETB.
Infinite sacrifice triggers.
Infinite death triggers.
Infinite creature tokens with haste.
Infinite token copies of each creature you control with haste except Midnight Guard.