Cast Spinal Embrace only during combat. Untap target creature you don't control and gain control of it. It gains haste until end of turn. At the beginning of the next end step, sacrifice it. If you do, you gain life equal to its toughness.
As long as your devotion to blue and black is less than seven, Phenax isn't a creature.
If I have Phenax in play, and my opponent plays Spinal Embrace targeting it, and then gains control of it, but does not have enough devotion to make Phenax a creature, what happens? Do they gain control of Phenax permanently?