Tempest's Rolling Thunder

How exactly is the damage calculated in relation to the number of rounds it lasts? As far as I can tell, you'll cap out the damage at 10d4 and the duration would be 10 rounds.... but that's at level 20... what about the other 10 extra rounds for a level 40 caster? What happens to those? Are they all at 1d4 or do they just poof? Either way I love the spell and wouldn't get rid of it wuthout some serious incentive, but it would be cool to know.

Also - why can't the spell be extended?

How exactly is the damage calculated in relation to the number of rounds it lasts?

The first round is at full damage (1d4 per 2 caster levels, rounded down). So, for a 10th level caster, the first round is 5d4. For an 11th level caster, it's 5d4. For a 20th level caster, it's 10d4 (and where this spell maxes out). The second and later rounds are one less d4 than the round before...so the 20th level caster's spell starts at 10d4, then 9d4, then 8d4, then 7d4...on down to 1d4 on the final round.

As far as I can tell, you'll cap out the damage at 10d4 and the duration would be 10 rounds.... but that's at level 20... what about the other 10 extra rounds for a level 40 caster? What happens to those?

The spell maxes out at 10 rounds for casters 20th level or higher. No extra rounds beyond the 10.

Also - why can't the spell be extended?

Because the maximum duration is 10 rounds. The spell cycles damage down by 1d4 each round, starting at the highest and going down to 1d4 on the last round. Would you really want a bunch of extra rounds of spell effect at 0d4 damage?

The Amethyst Dragon wrote:

Would you really want a bunch of extra rounds of spell effect at 0d4 damage?

Suggestion then; change the spell description to mention that it does end at ten rounds either way.