Fell Beast's Shriek

Each opponent chooses a creature they control. Tap and goad the chosen creatures. (Until your next turn, those creatures attack each combat if able and attack a player other than you if able.)

Splice onto instant or sorcery 2UR (As you cast an instant or sorcery spell, you may reveal this card from your hand and pay its splice cost. If you do, add this card's effects to that spell.)