Karai's Technique (Showcase) [Teenage Mutant Ninja Turtles]

Sneak {W}{B} (You may cast this spell for {W}{B} if you also return an unblocked attacker you control to hand during the declare blockers step.)
Choose one or both
Target creature gets +3/+3 until end of turn.
Target creature gets -3/-3 until end of turn. “The ninja who loses his temper, loses the battle.”Karai