Xenic Poltergeist

{1}{B}{B} · Creature — Spirit

{T}: Until your next upkeep, target noncreature artifact becomes an artifact creature with power and toughness each equal to its mana value.

Motor: se resuelve a mano

Rulings (2)

A noncreature permanent that turns into a creature can attack, and its {T} abilities can be activated, only if its controller has continuously controlled that permanent since the beginning of their most recent turn. It doesn't matter how long the permanent has been a creature.
Wizards of the Coast · 2008-08-01
Wears off at the beginning of the upkeep, not during upkeep.
Wizards of the Coast · 2004-10-04