The funny thing is that an overlay of the cooldown text is already implemented in the game.



The problem is that it only shows up when you highlight the skill. My suggestion is to keep the icon shadowed and show this cooldown text on all skills that aren't tied to the GCD natively on the hotbar. It is very aggravating to think that your skill is ready for use only to find out it still has 10-20 secs left to go. It's very hard to tell with the current implementation.