As of now, the timer for units units like wards, illusions and summon is a green circle that acts like a clock. Though it might be intentional that it is like that so that it resembles a clock, I and some others I have talked to don't like it too much. Maybe if they changed the timer from a circle to a thinner white (or any neutral color) bar above the health bar or below the mana bar. It is also easier to estimate how much time that unit still has left since the bar is longer and would update more visually.

If you guys like the circle better, then I have another suggestion. Maybe change the color of the circle depending on the time left. ie, green when it is just summoned/planted, yellow = 75% time left, orange = 50% time left, red = 25% time left. Or something along those lines.

What do you guys think?