Add Breath Weapon to Monster
 

I have the Game Mastery Guild and I am trying to add a breath weapon to a monster I have created. I have been able to add a breath weapon under the Offensive and Proactive Actions section but it's not showing up on the stat block and it doesn't have any damage listed in that section. How do I make this work?

For the generic Breath Weapon I can't find it either; the only thing I can find to set is the DC. Time to submit bug reports.

Yes, please submit this as a bug report. I think we'll all breathe easier once this is looked into properly.

Bug report submitted and acknowledged. For now the workaround is to use a Generic Ability or a Custom Weapon Attack as appropriate.

For new abilities, I recommend the "New Abilities (Unique to this Ancestry)" table at the very bottom of the Customize Ancestry table, rather than trying to hack existing abilities to turn them into something new - there's a lot more flexibility built into the generic ability than the fixed abilities. I just tested adding a new item called Breath Weapon, and it shows up in the Special Abilities list in the play tab and on the offensive abilities section of the statblock.

This is indeed what I decided to use. It still doesn't have damage options from the GMG but I was able to type it in the description.

Yeah, looking at my saved monsters it seems like a LOT of the Customize Ancestry sub-options have vanished from the UI.

EDIT: I've submitted the issue as a bug report and have been notified that it's being looked into.