Kodama of the East Tree | Cloudstone Curio

Cards

Helm of the Host attached to
Kodama of the East Tree.
An additional nonartifact permanent card in your hand that you are able to play.
An additional nonartifact permanent card on the battlefield that shares a type with the card in your hand and that has an equal or lesser mana cost.

At the beginning of combat,
Helm of the Host triggers, creating a nonlegendary token copy of
Kodama of the East Tree.
When the token enters the battlefield,
Cloudstone Curio and the original
Kodama of the East Tree trigger; decline to use these abilities unless desired.
In your second main phase, play the nonartifact permanent in your hand.
When it enters the battlefield,
Cloudstone Curio and both copies of
Kodama of the East Tree trigger.
Resolve the
Cloudstone Curio trigger, returning the other nonartifact permanent from the battlefield to your hand.
Resolve the first
Kodama of the East Tree trigger, putting the permanent you returned in step 5 from your hand onto the battlefield.
When that permanent enters the battlefield,
Cloudstone Curio and the second
Kodama of the East Tree trigger.
Resolve the
Cloudstone Curio trigger, returning the permanent you played in step 3 from the battlefield to your hand.
Resolve the
Kodama of the East Tree trigger from step 7, declining to use it unless desired.
Resolve the remaining
Kodama of the East Tree trigger from step 4, putting the permanent you returned in step 8 from your hand onto the battlefield.
Repeat from step 4 any number of times.
This combo results in Infinite ETB and Infinite LTB if a permanent involved is a creature, and/or Infinite landfall triggers if it is a land.

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