If you control "Regulus, the Prince of Endymion": Activate 1 of these effects;
• Destroy 1 monster your opponent controls that battled this turn.
• When a Normal or Quick-Play Spell Card is activated: Negate that effect.
During your Main Phase: You can banish this card from your GY, then target 1 "Regulus, the Prince of Endymion" or 1 monster that mentions it in your GY; Special Summon it. You can only use each effect of "Arrow of Regulus" once per turn.