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Infinite ETB.
Infinite storm count.
Infinite creature tokens.
Infinite magecraft triggers.
Infinite landfall triggers.
Infinite copies of any permanent on the battlefield.
Infinite mana permanents can produce.
Return all instant and sorcery cards from your graveyard to your hand.
Infinitely large creature until end of turn.

1. Cast Doppelgang by paying ({15} magic symbol) Magic Symbol (15)({G} magic symbol) Magic Symbol (G)({U} magic symbol) Magic Symbol (U).

2. Each Shipwreck Dowser you control prowess ability triggers, giving each of them +1/+1 until end of turn.

3. Resolve Doppelgang, creating five token copies of Shipwreck Dowser and of the four mana-producing permanents.

4. When the Shipwreck Dowser tokens enter the battlefield, they trigger, returning Doppelgang and up to four other instant or sorcery cards from your graveyard to your hand.

5. Activate seventeen of the mana-producing permanent tokens by tapping them, adding at least ({15} magic symbol) Magic Symbol (15)({G} magic symbol) Magic Symbol (G)({U} magic symbol) Magic Symbol (U).

6. Repeat.