Magical Girls don't have to be random, again you can be it and set it however you want, it's just One loves to make a skill that let her cast a number of random spells and use a random number generator to determine which one she will use, but you don't have to do that, and if you can't decide between a dragon tamer or a gunner why not be both? You can be a dragon tamer with the ability to tame wyverns and call your pet, but use guns, having your dragons on the front lines stopping the monsters from attacking you or be a gunner with the ability to have a pet and tame wyverns, the only difference is between those two options would be the class skill you would have, and the fact that the secondary class would always be half the level of your main class. So if you were level hundred, your secondary class would be level 50 which basically means you could use a load of their skills but not any that are really powerful.