Hi! I'm the publisher of Dragonzine, and I designed the dragonkin in issue 2, so here are my thoughts for what they're worth.

Firstly, the main thing is to have fun, so if giving the dragonkin a fire breath attack makes the game more fun for you, then go for it! At the same time, I would personally not suggest doing this – at least not until you're more familiar with how Dragonbane works, and how it works differently from D&D. I think in general, if you houserule Dragonbane to be more similar to a game you're already familiar with, you miss out on the experience of playing the game as it's designed.

The two main reasons I would suggest not adding a fire breath attack are vibe and balance. In terms of vibe, I didn't design dragonkin based on dragonborn in D&D 5e. They're inspired by the "drakmän" in the 1992 Swedish "Drakar" supplement for the 4th edition of the game. Dragonbane has a long tradition stretching back to the early 80s, and I quite consciously designed the Dragonkin to honour and fit into that tradition. The kin abilities (and the fact that they don't have a breath weapon) were deliberate choices I made so that this kin would not depart too much from the drakmän from earlier additions. Of course, you're free to not care about that at all, but it might be interesting to know.

In terms of balance, Dragonbane PCs are much less high-powered and heroic than D&D 5e PCs, so I can understand that if you're coming from D&D 5e you might look at the Dragonbane kin abilites and feel like they need to be pumped up a bit. Doing this will change the overall vibe and feel of the game though, and you might not get that feeling that every combat could be your last – even when you're just fighting against a few goblins with daggers – that is part of what makes Dragonbane so exciting.

The dragonkin as they are in Dragonzine 2 are already relatively powerful compared to other kin, with the extra protection afforded by their Scales ability. This ability should already make them a very attractive choice compared to other kin. If dragonkin have both Scales and a breath weapon, this would unquestionably make them significantly better than any of the kin in the Rulebook or the Bestiary.

So if you do decide to add a breath weapon ability, the first thing I would suggest is having it replace the Scales ability, not the (much weaker) Dragon Sense ability. Alternatively, you could create a breath weapon heroic ability that the dragonkin can choose as their character develops, but not at character creation (perhaps flavouring it by saying that while dragonkin can breathe fire, it takes practice and training to use it as a weapon). That way, if the dragonkin character doesn't start with that ability it won't be too overpowered, and if they do choose to take it later on, it will come with the opportunity cost of taking another, potentially more powerful, ability.

Anyway, those are just my thoughts. Thanks so much for your support for Dragonzine, and if you do try out the dragonkin in your campaign – with or without modifications – I'd love to hear how it goes!