When clicking on an ability that is not yet cooled down, could you not only display the stats (damage, effect, cast time) but also the amount of time remaining until the cool down is complete?
Even better, like the "use" text that displays before an ability is selected, how about text that says "wait" for abilities not yet cooled down. Waiting would grant no defense benefits, but would be useful when a desired ability has 0.03s of cooldown left, and no other ability with a casting time less than 0.50s is available.