Cast Twinflame by paying 1, targeting Spark Double as copy of Garth One-Eye, creating two token copy of Spark Double as a copy of Garth One-Eye.
Activate first Garth One-Eye token by tapping it, choosing Black Lotus.
Cast the copy of Black Lotus.
Activate Black Lotus by tapping and sacrifing it, adding .
Activate second Garth One-Eye token by tapping it, choosing Regrowth.
Cast the copy of Regrowth targeting Twinflame, returning it from your graveyard to your hand.
Cast Twinflame by paying its strive cost, targeting two token copy of Spark Double as a copy of Garth One-Eye, creating four token copy of Spark Double as a copy of Garth One-Eye.
Activate the first three Garth One-Eye token by tapping it, choosing black Lotus.
Cast the copy of Black Lotus.
Activate two Black Lotus by tapping and sacrificing it, adding .
Activate third Black Lotus by tapping and sacrificing it, adding .
Activate the fourth Garth One-Eye token by tapping it, choosing Regrowth.
Cast the copy of Regrowth targeting Twinflame, returning it from your graveyard to your hand.
Repeat from step 7.
This dizzying loop transforms Garth One-Eye into an engine of absolute abundance by multiplying him exponentially. It all begins when you copy Garth One-Eye with Spark Double, stripping away the legendary restriction so you can have multiple copies on board; this is further supercharged by Doubling Season, which ensures any token-copy creation or counter placement goes into overdrive. You then use Twinflame to replicate your non-legendary Garth One-Eye copies, letting you generate cascading waves of Black Lotus and Regrowth mana and recursion to continuously recast Twinflame for an endlessly compounding army.