From what I gather from various posts many seem to want a dragon-like mutation category, myself included, but it’s seen as potentially too fantasy. I have a possible solution for 2 physics problems that have been brought up, specifically concerning the idea of dragon wings flight, and a fire breath weapon.
Animal Planet did a special about dragons where they suggested that real dragons might have been able to both fly and breath fire due to bacteria in their system the built up hydrogen, which their body would store in a gas bladder. Hydrogen reduced their weight since its lighter then air, and by chewing platinum ore and having residue of it in their mouth allowed them to breath fire, since hydrogen ignites on contact with platinum.
It seems simple enough to make a mutation that gives the wings, which on their own would have drawbacks like the bat wings, more in the way then helpful. Then another mutation for the hydrogen bladder, which negates the wings penalties, and replaces them with the same benefits bird wings have. and then the third which lets you expel the contents of your gas bladder in a gout of fire, but negates the bonuses of the gas bladder mutation for a set amount of time and gives you back the full penalties of the wings until it has time to recharge. Possibly also include some requirement (and ability) to find platinum in game and eat/wear/something it in order to be able to use the fire breath this way.
Other mutations that would seem logical as well would be a form of night vision, infrared vision, claws, a bite, dragon scales armor which might also include some protection from fire, a tail.
on an unrelated note, this is my first post, I love cataclysm, have been playing for over a year so far and I hope to see it continue its steady improvement and possibly help with some brainstorming and ideas myself in the future