If you have never built a Blink or Flicker deck, consider throwing one together and giving it a spin
The ability to lock the opponent out of the game (with a card tutored from your sideboard) for six mana is incredibly strong since it only takes a single sideboard slot in a deck that already runs Karn
just Griffnaut Tracker, Cease / Desist, sometimes Gravestone Strider, and a handful of rares
Peregrine Drake untaps five lands when it enters the battlefield, so each time you exile and bring it back, you get three additional mana
Sure, there are a couple of reasons other than spell count to mill a specific player, like, scry, Sams Desperate Rescue, or Haunt of the Dead Marshes
But remember, dealers purchase collections at wholesale prices