The lion drake, or dragonne, should be about 12 feet, so scale up or down based on the size of miniatures used. Keep in mind that they are territorial. They will attack anyone who enters their territory. They are fairly neutral, so if people leave their area, they will not chase. They have small wings so won't fly too high or far. This isn't to say they won't grab a character and fly them high up and drop them on the rest of the party, though! But be most careful of the roar or getting knocked prone by their pounce attack!