A magical explosion can occur for one of two reasons:
- A magic trap exploded.
- A bag of holding was just destroyed, by putting a charged wand of cancellation, bag of tricks, or another bag of holding inside it.
In the first case, your power will be slightly increased, possibly including your max power. There are many other explosions in the game with magical sources, but these are the only two which are explicitly described as "magical explosions."