Play this when you have good black and blue mana
Oh, and if you drop it during your main phase
Again, my ordering isn't absolute here
I know Mono-Blue Devotion has floated around the fringes of playability for a while, but due to that decks focus on Nyx Lotus and Corridor Monitor, it prefers Arcanist Owl
But if you're on Zhulodok or Kozilek you'll want the following: Ancient Tomb, Eye of Ugin, Urza's Saga, Demolition Field, The Mycosynth Gardens, Vesuva, Thespian's Stage Lands Mana Crypt, Mana Vault Ramp The One Ring, Palantir of Orthanc Card Draw Portal to Phyrexia, Cityscape Leveler Removal Kozilek, Butcher of Truth, Ulamog, the Ceaseless Hunger, Ulamog, the Infinite Gyre, Emrakul, the Promised End Eldrazi 3 Down, 1 To Go
Crispin lets Energy be attached from the deck to any Pokmon in play, then adds another Energy card from the deck to the hand, which helps consistency a lot