Using this staff vs rogues: In the 1.25 seconds taken to charge this staff, a rogue can unleash a full combo taking a mage down to around 60% health, while the rogue stays at 100%???

Using the staff vs tanks: Against tanks I am constantly moving and using my long range spells to avoid incoming damage, the chance of me releasing more then 1 skill in a concencrate range....

Using the staff vs mages: Mages with a glintstone gun will already have an advantage with consitently hitting for more damage then I am. My concencrate will give me a slight advantage in the damage department, but by that time the opposing mage has landed 2-3 skill shots on me and consistently hit for about 30 more skill damage(including damage reduction) per skill shot.

In clash: Half the players are not in range of concencrate because of the small radius. If a rogue were to try to get in range they would likely get destroyed by aoe to deal an extra 40 damage? Tanks get a good buff from this however.