The mana cost can be reduced if you tap combo pieces or other applicable permanents while activating
Katara's waterbend ability the first iteration. As the combo will net ({C} magic symbol) each iteration, you can forego sacrificing and/or tapping both tokens on some loops.
Results
Infinite card draw.
Infinite draw triggers.
Near-infinite +1/+1 counters on a creature.
Near-infinite ETB.
Near-infinite LTB.
Near-infinite colorless mana.
Near-infinite creature tokens.
Near-infinite death triggers.
Near-infinite sacrifice triggers.
Metadata
In 1 deck according to EDHREC.
Bracket Tag
This combo has been estimated to be Exhibition (Bracket 1+).