Scaling SU and Sp abilities (breathweapons)

[Albert_Fish]

how do i scale a breath weapon? are they even scaleable? or does a 42 HD Frost Worm still only do 15 d6 points of damage witha Ref save 15?

if i want it to increase how would i do that and still rely upon norms created by WOTC ( even if its not according to the rule, per se)?

 

[the Jester]

I don't know about increasing the damage, but I scale the DCs of saves for monster abilities when I advance the monster... DC 10+ half HD + ability mod (con for breath weapons). After all, the CR is increasing- it only seems right that the DCs should go up.

 

[Geocorona]

The Open Gaming Foundation site has the DC at 22, but that could be wrong. http://www.opengamingfoundation.org/srd/srdmonstersfg.html If that's the real DC, it probably is linked to CON, and any CON increase with size increase will have to be added to the formula below.

As far as I can see, you'll have to use home brew rules. Here's how I approximate breath weapon scaling:

Scaling Breath Weapons
======================

* increase line/cone range to 133%/125% for each size class increase, round to closest 5.
* add 1 damage die and increase DC +1 for every 2 added hit dice, round down.
* If CON changes, DC = 10 + HD/2 + CON modifier.

Huge to Gargantuan
30 ft. => 30 * 1.25 => 35 or 40 ft.

14 to 42 HD => (42-14)/2 => 14 added to damage die & DC
DC 15 => DC 29
15d6 damage => 29d6 damage

range: 35 or 40 ft.
damage: 29d6
DC: 29
DC: 38 if old DC was really 22 and 4 points of CON are added in size increase