A cap should be added to prevent getting to 100% cooldown.

[doctorpupy]

One can achieve 100% cooldown rate for their charged ability if they get 1% cooldown from the golden vases throughout the game, as well as
32% CDR Superior Cooldown
20% CDR Rapid Recharge (charged ability only)
15% CDR Spiritual Overflow
12% CDR Diviner's Kevlar
(can also get Soul Rebirth for 10% but isn't necessary).

and a casting powerup (which grants 20% CDR).

This is very silly, but it is a huuuge problem on Vindicta's ult. If she has 100% cooldown she never leaves her scope and can fire as fast as she can fire...
Video using mousewheel.

 

[Yoshi]

We are making cdr stacking diminishing in an update todaay