Chthonian Nightmare | Pitiless Plunderer

Cards

All permanents on the battlefield (
Kaya with two or more loyalty counters on it).

You control another nontoken creature.
You have a creature card in your graveyard.
The total mana value of the creature on the battlefield and the creature card in your graveyard is at most 6.

Activate
Kaya's second loyalty ability by removing two loyalty counters from it, causing you to double any tokens you create this turn.
Activate
Chthonian Nightmare by paying an amount of ({E} magic symbol) , sacrificing a nontoken creature and returning
Chthonian Nightmare from the battlefield to your hand.
When the creature dies,
Pitiless Plunderer triggers, creating two Treasure tokens due to
Kaya.
Resolve the
Chthonian Nightmare ability, returning another creature from your graveyard to the battlefield.
Activate two Treasures by tapping and sacrificing them, adding ({1} magic symbol) ({B} magic symbol) .
Cast
Chthonian Nightmare by paying ({1} magic symbol) ({B} magic symbol) .
When
Chthonian Nightmare enters, it triggers, causing you to get ({E} magic symbol) ({E} magic symbol) ({E} magic symbol) .
Repeat from step 2.

If the combined mana value of the creatures is less than 6, this combo will net infinite energy counters.

This combo has been estimated to be Exhibition (Bracket 1+).