you can't cast it without sacrificing a creature, and you can't sacrifice additional creatures
Arthur attacks, and you happen to put Bloodthirster in play
I dont think that were going to see this become a huge staple with decks running four copies, but I do think that multiple decks like Jund, Dredge and Titan will start running 1-3 copies and be able to replace a basic land with it, potentially opening up other removal slots for different cards instead

Julius Jumblemorph Ego Erasure Feisty Spikeling Firdoch Core Fire-Belly Changeling Flock Impostor Formless Genesis Game-Trail Changeling Gangly Stompling Ghostly Changeling Gladewalker Ritualist Graveshifter Guardian Gladewalker Impostor of the Sixth Pride Irregular Cohort Littjara Littjara Glade-Warden Littjara Kinseekers Masked Vandal Maskwood Nexus Mirror Entity Mischievous Sneakling Mistform Ultimus Mistwalker Moonglove Changeling Moritte of the Frost Morophon, the Boundless Mothdust Changeling Mutable Explorer Nameless Inversion Omni-Changeling Omo, Queen of Vesuva Overlord of the Hauntwoods Personify Prideful Feastling Realmwalker Rooftop Percher Runed Stalactite Shapesharer Shields of Velis Vel Sizzling Changeling Skeletal Changeling Springleaf Parade Stalactite Dagger Taurean Mauler Three Tree Mascot Turtleshell Changeling Universal Automaton Unsettled Mariner Valiant Changeling

Not Dead After All is a way to save a creature from dying, as it will return to the battlefield with a Wicked Role token on it