The glowing bead created by
delayed blast fireball can detonate immediately if you desire, or you can choose to
delay the burst for as many as 5 rounds. You select the amount of
delay upon completing the spell, and that time cannot change once it has been set unless someone touches the bead (see below). If you choose a
delay, the glowing bead sits at its destination until it detonates. A creature can pick up and hurl the bead as a thrown weapon (range increment 10 feet). If a creature handles and moves the bead within 1 round of its detonation, there is a 25% chance that the bead detonates while being handled.