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

Cost: 1 W B 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