The deck's plan is surprisingly simple: mulligan aggressively to find Kami of Whispered Hopes. Kami is basically Marwyn but with one massive upgrade: it makes mana of any color rather than just blue mana, which is key since it allows us to use the mass-card-draw spells that blue has to offer. Actually, we can make an even better version in our current Standard, with Kami of Whispered Hopes replacing Marwyn, the Nurturer.
I recently realized that we have all the pieces to revive the Marwyn combo in our current Standard.
Basically, it was like a Standard version of Twiddle Storm! The idea was to play a bunch of pump spells that can untap Marwyn in order to let it tap for an increasing number of mana and eventually use that mana to win the game somehow. If you've been playing Magic for a while, you might remember an infamously janky combo from a few years ago involving Marwyn, the Nurturer, a three-drop that taps to make mana equal to its power.
