In theory, a booster box could contain zero mythics and all bulk rares, or it could contain a complete set of foil mythics
Ramping into Showdown turn three, four or five gives you potential to exile a Dragon, The Kami War Flip or even another Showdown to then play those cards with your ramp on your next turn
Plus, Unctus will have ward as long as this robot dog is untapped
Jilt (Invasion/Planeshift/Apocalypse) By the same token, without the kicker Jilt is an overcosted Unsummon - although I can't stress enough how important bounce spells are in limited for blue
For regular upgrades I highly recommend: Vito, Thorn of the Dusk Rose, Mondrak, Glory Dominus, Anointed Procession, Parallel Lives, Eerie Ultimatum, and you can also run the Cat Oven combo with Cauldron Familiar + Witch's Oven + Clock of Omens, and there's the Ballista Combo Heliod, Sun-Crowned + Walking Ballista, and finally the Exquisite Blood Combo since the deck already runs the other piece Sanguine Bond One Down, Three to Go
In particular I really Loyal Apprentice and Loyal Drake, since they can give you solid benefit early in the game before you get your commander creature on the battlefield