Oko, Thief of Crowns The numbers are just wrong on Oko, Thief of Crowns
That alone isn't enough to accept the damage from tapping this for mana, but a few minor synergies can push it over the edge
Then you can overwrite literally anything
Just one little creature can give major boosts to every other Sliver in play, multiplying your army many times over with just a could of creatures
If your graveyard is sufficiently stocked, its entirely possible that once you draw Recurring Nightmare, it is the only spell youll want to play for the rest of the game
I love the idea of gating progress for the first pack behind, say, having to have three characters questing on the same turn