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.
You control at least one mana-producing land.
Steps
Activate up to two lands by tapping them, adding at least ({1} magic symbol) .
Activate Midnight Guard using The Jolly Balloon Man's ability by paying ({1} magic symbol) and tapping it, creating a token copy of Cloud of Faeries that is a 1/1 Balloon with flying and haste in addition to its other types.
When the Cloud of Faeries token enters the battlefield, it and Midnight Guard trigger.
Resolve the Cloud of Faeries token's trigger, untapping up to two lands.
Resolve the Midnight Guard trigger, untapping it.
Repeat.
Notes
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 mana lands you control can produce.
Infinite creature tokens with haste.
Infinite untap of lands you control.
Infinite token copies of each creature you control with haste except Midnight Guard.