24 Nov 2014
The mana generated by the last ability can't be spent to activate abilities of Dragon sources that aren't on the battlefield.
24 Nov 2014
You can use mana generated by the last ability to pay an alternative cost (such as a dash cost) or an additional cost to cast a Dragon spell. It's not limited to paying just that spell's mana cost.
24 Nov 2014
Notably, turning a face-down creature face up isn't an activated ability. If you manifest a Dragon creature card or cast a Dragon creature card face down using the morph ability, you can't use mana generated by the last ability to turn that card face up.
24 Nov 2014
An activated ability appears in the form “Cost: Effect.”