You can only activate “Curse of Royal” as a chain to a Spell or Trap Card that would destroy 1 (and ONLY 1) Spell or Trap Card.
You can use Curse of Royal against cards like “Magic Jammer”, “Seven Tools of the Bandit”, “Solemn Judgment”, “Curse of Royal”, “Mystical Space Typhoon”, “Dust Tornado”, “Magic Drain”, “Riryoku Field”, “Judgment of Anubis”, etc.
You cannot use “Curse of Royal” against “Heavy Storm” or “Harpie’s Feather Duster”.
Netrep Rulings:
You can activate Curse of Royal as a chain to a Spell or Trap Card that would destroy 1 (and ONLY 1) Spell or Trap Card.
You can use Curse of Royal against Magic Jammer, Seven Tools of the Bandit, Solemn Judgment, Curse of Royal, Mystical Space Typhoon, Dust Tornado, Magic Drain, Riryoku Field, etc.
You cannot use Curse of Royal against Heavy Storm or Harpie’s Feather Duster.
Curse of Royal can only be used against Spell & Trap Cards.
If a card can destroy either a Spell or Trap Card or a Monster Card, like “Raigeki Break” or “Solemn Judgment,” it must be targeting 1 Spell or Trap Card to activate “Curse of Royal.”
Netrep Q&As:
Q: Can you flip “Curse of Royal” to negate and destroy “Raigeki” if one of your monsters has an equip card attached that would be destroyed once the monster is destroyed?
A: No, because “Raigeki” does not specifically destroy one Spell or Trap card in your Spell and Trap card zone. You can use it against Spell or Trap cards like “Magic Jammer,” “Seven Tools of the Bandit,” “Solemn Judgment,” “Curse of Royal,” “Mystical Space Typhoon,” “Dust Tornado,” “Magic Drain,” and “Riryoku Field.” Curtis Schultz, 12/04/2003