I found a reasonably viable use for Ancient Magic today. It's fairly niche, but it's a start
Here it is:
Used when soloing enemies. In this example I used Tornado.
- Stand close enough to enemy to use Spirit Dart, but out of aggro range.
- Cast Tornado on self.
- Cast Spirit Dart on enemy. (this could be Choke II if in range)
- Begin regular chains of Choke II, Aero, Aero II.
- By the time Tornado activates, enemy will be in range and take Tornado damage.
Essentially Ancient Magic lets you "pre-load" damage. The casting time doesn't matter, since it's done before combat begins. The MP cost is high, but for fighting single enemies is not critical. The time delay is actually GOOD, since it allows time for the enemy to approach within range.
Alternately, it can be cast on the main tank, who then pulls. Unfortunately, the caster of the AM spell still receives all of the enmity for the spell damage.
Regarding enmity, I'd like to propose that some of the enmity from the activation of an Ancient Magic spell be received by the target (if a player) of the spell. This would make the spell IMMENSELY useful, as a way to generate more enmity on the tank, while avoiding generating it on yourself.
Perhaps having ALL enmity from the damage dealt register to the (player) target would be too overpowered, but splitting it might not be. Currently this is not the case, but I'm hoping that SE would take this into consideration.