({G} magic symbol) ({G} magic symbol) plus an additional ({G} magic symbol) if you don't control an untapped green creature available.
Steps
Cast a copy of
Channel by paying ({G} magic symbol) ({G} magic symbol) .
Activate the ability granted by
Channel four times by paying 4 life, adding ({C} magic symbol) ({C} magic symbol) ({C} magic symbol) ({C} magic symbol) .
Cast
Sprout Swarm with buyback by paying ({4} magic symbol) and either tapping a green creature if you're able or paying an additional ({G} magic symbol) .
Aetherflux Reservoir triggers, causing you to gain 1 life for each spell you've cast this turn.
Resolve
Sprout Swarm, creating a 1/1 Saproling creature token and returning
Sprout Swarm to your hand.
Repeat from step 2.
Notes
The life requirement can be lowered if you've cast spells beforehand this turn and/or if you supply additional mana. After the first loop, you'll want to tap the Saproling to reduce
Sprout Swarm's cost by ({G} magic symbol) via its convoke ability.
Results
Infinite ETB.
Infinite colorless mana.
Infinite damage.
Infinite lifegain.
Infinite magecraft triggers.
Infinite storm count.
Infinite tapped creature tokens.
Metadata
In 2 decks according to EDHREC.
Bracket Tag
This combo has been estimated to be Exhibition (Bracket 1+).