While this Magic card is in your hand, when your opponent summon a Spirit through an effect, you can use it without paying the cost.
Flash - Destroy 1 opposing Spirit of 10000BP or lower. If you have a Spirit containing the name "Wurm", instead destroy 1 opposing Spirit with 20000BP or lower. The Spirit destroyed by this effect cannot activate its effects.
Ruling: If the summoned Spirit has a summon effect, and you choose to use this magic from hand, the player during that turn chooses which effect to activate first.