Sprite Dragons can't be considered as having pure giant dragon bloodlines, because their physical bodies are very weak, but their magical talents are off the charts!
Moreover, they possess talents for all elemental magic, and once a single individual advances to the level of a Lord Boss, with some cost, it can release a Minor Forbidden Spell on its own.
What's most outrageous is that the Sprite Dragons, with their advantage of having talents for all elemental magic, are innately capable of performing Minor Forbidden Spells of each element!
As for other elemental giant dragons, their corresponding elemental dragon language spells all have damage bonuses. Even though they might not be able to cast Minor Forbidden Spells, their spells' power is definitely a level stronger than those released by the Black Dragons.