A Finisher could also be something as simple as an extra combat spell such as: Grim Reaper's Sprint, Karlach, Fury of Avernus, Relentless Assault, and Seize the Day
As long as a blue Creature-centric deck exists in Standard, though, theres a good chance Subterranean Schooner is a big part of it
Into: The Mill-Meoplasm In a game with very full graveyards, I suspect that Boneyard Parley is going to lead to some absurd situations
LANDS THE ALLIED FETCHLANDS While I am more inclined to play enemy colored pairs myself, having these finally make an entrance back into the game is going to help a lot of players add consistency to mana bases
For example, a 1/1 Elemental creature that enters under your control "with a +1/+1 counter on it" won't receive an additional +1/+1 counter