Oracle Text

Whenever you cast a spell, put the cards in your hand on the bottom of your library in any order, then draw that many cards.

Card Rulings

10/1/2005 Whenever you cast a spell, Mindmoil’s ability triggers. The ability will resolve before the spell does.
10/1/2005 After Mindmoil’s ability triggers, players may cast instants and activate activated abilities. Each time you cast an instant spell “in response,” Mindmoil’s ability triggers again.
10/1/2005 After Mindmoil’s ability resolves, but before the spell that triggered it does, you can cast instants from your new hand of cards. Each time you do, Mindmoil’s ability triggers again.