The damage for the spell delayed blast fireball is listed as:
The spell’s base damage is 12d6. If at the end of your turn the bead has not yet detonated, the damage increases by 1d6.
The spell's duration is "Concentration, up to 1 minute".
Does this damage increase repeat on each of your turns throughout the spell's duration?
Or does it only apply to the turn when you cast the spell?
I tried to draw comparison to the 3.5e version of the spell, but according to the d20 SRD, there is no damage bonus for delaying the blast in D&D 3.5e; the spell is simply more powerful than fireball.