Nightsister Shadow Killer

Rank III - Knight
Stealth, Deadly Strike, Ambush
While this card is on the field, once per turn, pay {x} to place Spirit Ichor on this card equal to X.
Shadow Phase (Remove two Ichor from this card as
cost. After this card attacks or would be destroyed, you
can remove this card from the field until the start of
your next turn, then it returns at your draw.)