dave2008
Legend
Couldn't you simply have the dragon create areas that are on fire as Iserith suggested, and deal 1d10 damage to any creature that ends their turn in that area? And every time a creature takes fire damage from the dragon (directly or indirectly), they automatically catch fire (if they wear flammable fabrics), which can be extinguished by spending an action to extinguish the flames. You don't need to be carrying gallons of water, you just need to roll on the ground a bit, and do your best to douse the flames. The target then take 1d10 fire damage each round until the fire is extinguished.
Yes you could and I think that is closer to a general rule for 5e, but I am specifically looking for something more.
Hmmm, that is not what I intended with the water comment. The intent was that you could be doused with water or take an action and make a save to extinguish the flames. The water is not required, but if have it, it is a get a jail free card.
By the way, 6d6 seems like a bit much for just being on fire. Are the players being hit with dragon fire, or being dowsed with napalm?
Magical naplam, yes that is the effect I was going for. I guess I hit right on

Breath weapons are plenty scary as is. No need to increase the damage that much.
I disagree. For an ancient red I typical raise the average damage so that it would reduce a wizard without resistance, and that fails a save, to 0 HP. This revision is actually a little kinder as you probably keep the 91 fire damage of the MM instead of the 150 +/- fire damage I normally use.