My casual Merfolk Build. Everything dies to lightning bolt, and this is not the way to beat Drake.

Weight of Conscience acts as a one time use tap everything button at instant speed for life gain and token production and Mine Excavation lets you buy it back.

Field Surgeon is the unsung Hero of this deck. Mothdust Changeling is awful; he's essentially an enchantment that dies to removal. Field Surgeon has protection with a relevant cost built in. He is literally the merfolk creature you want, even though he isn't a merfolk.

Outside of that, lots of card draw to keep the gas coming, and Holdout Settlement and Springleaf Drum give you lots of ways to tap your dudes.

Maybeboard is possible inclusions instead of think twice as a card to tutor for. Sprout swarm is probably a great card, but it just doesn't match the flavor I'm going for. If I were to make this a not-casual deck, it would probably get at least one slot for sure. Inside out was recommended as possible removal, but I'm just not really sold on it, even as a one of. I'd rather go for weight of conscience, or Mine Excavation to get more weight of conscience.