Casting the copy of the prepared spell works just like casting any other spell. You have to pay its cost, and you have to follow the timing rules put in place by its card type. If it's a sorcery like Rampant Growth, you can cast it during your main phase if the stack is empty. If you cast a prepare spell from exile, the prepared creature becomes unprepared, meaning it loses the prepared designation.

The ability word opus highlights triggered abilities that trigger whenever you cast an instant or sorcery spell. Each opus ability has an initial effect and an additional or alternative effect if you spent five or more mana to cast the spell that caused the opus ability to trigger.

你可以从你的坟墓场施放具有返照异能的牌。若你如此作，你需支付其返照费用，而不是支付其法术力费用。返照异能并不会改变你能施放该咒语的时机，所以具返照异能的法术仍只能在你的主阶段中施放。此外，以返照方式施放咒语并不会改变其法术力值。法术力值永远基于咒语的法术力费用来计算，即使你支付了替代性费用来施放它。

Paradigm is a new keyword that appears on a cycle of sorceries and gives them true staying power. The first time a particular spell with paradigm resolves for you, you exile it. From that point forward, at the beginning of each of your first main phases, you may cast a copy of it without paying its mana cost. Casting each of these copies is optional, and you'll have the opportunity to cast one on each of your turns no matter what happens to the previous ones.