I've pondered and pondered, trying to figure out what SE was thinking of with Ancient Magic. The facts that they are class-specific, cost 100 MP, have a six second cast time, and can be cast on other players (not just enemies) -- all these lead me to suspect that SE really had some in mind for these. However, in the end, it just doesn't seem to be there.

My current best guess is that Ancient Magic was tuned for the Alpha version of combat, and never adjusted. Back in alpha the stamina bar had to fill completely, making combat about 5 X slower than now. In that type of situation, the six second cast time and 30 second delay would make AM comparatively more powerful.

But in the current system .... no one yet has found any practical use for them.

My most fun use so far is to cast them on people standing around at the Adventurer's Guild, or on people crafting by the repair NPC, just for kicks. A bit weak for my class-specific, class-defining rank 44 spells