Mana Accellerator? Mystic Egg?

[City Builder]

Okay, so I'm a first timer to KB AP, and played a little ways in but starting over so that the camera mod can take effect since it only works on new games.

Im to choose a dragon as everybody knows, but what is mana accellerator?

I already looked in the stickied info thread, but it only lists what each dragon gives which is what is listed in the game so I'm still left wondering what dragon to pick as a mage and does it even matter? Seems to me that as the dragon levels up Im given choice to expand on his repetoire of skills anyway, so is it just a matte of choosing the color I find pleasant or what?

And of course, what is this mana accellerator?

Thanks,