It gives black mana untapped which is a big selling point, and its activated ability can actually kill something problematic in the early game
In fact, its basically broken
Best MTG Innistrad: Crimson Vow cards Cemetery Prowler Avabruck Caretaker // Hollowhenge Huntmaster Jacob Hauken, Inspector // Hauken's Insight Savior of Ollenbock Mirrorhall Mimic // Ghastly Mimicry Lantern Flare Ulvenwald Oddity // Ulvenwald Behemoth Olivia, Crimson Bride Alchemist's Gambit By Invitation Only There are some incredibly powerful reprints in Innistrad: Crimson Vow, with the likes of Thalia, Guardian of Thraben making their return, Splendid Reclamation being, uh, reclaimed and even Hero's Downfall making a move from rare to uncommon
My favorite targets are goblin lords that can hit the field between the first strike and normal combat damage, squeezing an extra point of damage out of the Warren Instigator
Im not talking about Siege Rhino, where the stats are just off the charts
Flying and vigilance, plus becoming a growing threat, more than make up for the double-blue pips