http://lucy.allakhazam.com/spell.htm...07&source=Live
http://everquest.allakhazam.com/db/s...tml?spell=1707
No significant changes to the spell since it's addition to the game based on what's available in the history of this spell. Wiki says 400 mana but where did that come from? It's wiki.. I wouldn't trust it. Both sources there say 750 mana to cast.
As far as the spell breaking 20 seconds later it has a set duration of 8 ticks, so that is either a bug if it truly lasted 20 seconds, or your measurement of the time that the spell lasted was subjective.
Again, 15 minutes seems over the top and a subjcetive measurement, as the recast time says 300, which would be 5 minutes. If the recast time is actually 900 then it should be adjusted.
This spell is a guaranteed charm for 48 seconds, which casts 750 mana and can only be used once every 5 minutes.