This style of game play is similar to another one that has been out for years. I will not list the name of the game unless asked but most players should know.
Personally cooldown is not a factor in that game and should not be so in this one. I think a solution is buffing/nerfing classes to make each one able to hold their own in the same scenarios as the other classes.
1. PVP- Give warriors a gap closer or AoE
2. PVE- Reduce MP cost of some skills
- This will make other classes more dependent on MP; to use skills more
- Since MP was introduce all class should need it not just one
3. Maybe allow MP or HP stats on armor
- Veteran players know of the "Glass Cannon" build would appreciate this
- Of course the boost is not that big but sustainable enough
There is actually a lot of flaws with MP reduction, in truth triple shot is more powerful than the average swing of a wand or weapon because of its range.
Overall, if the general public is at a lower (100 and lower) level then the MP reduction cost could be beneficial. Higher levels I would only recommend the warrior gap closer skill/ AoE and the MP/HP stat on armor.
Phearsom
"Fear and Loathing"