A small buff/QoL change for Skarner?

The issue:

Skarner's passive is built on a 3 stack system, which is then finalized by an auto attack. Currently, his passive is limited by a cooldown for stack application on a previously stunned target, instead of a cooldown for stun re-application. I think this cooldown is about 6(?) seconds.

What this means is that the cooldown for repeat stuns on Skarner's target isn't truly 6 seconds, but 6 seconds + variable amount, depending on whether he can maintain range with his target to keep applying stacks.

My biggest pain point with Skarner's current state, is that I have no indicator to keep track of when I can start applying stacks again, which also leads into an unknown amount of time until I can get my next stun off. It's not impossible to tell, but it's just more pain-staking, compared to other characters who have better readability and reliability with their crowd control. This plays a big role in whether you're able to tell if you can win/survive a duel/fight.

My suggestion:

Change his passive so that the cooldown applies to stun re-application instead of stack application. This would mean that after Skarner stuns a target with his passive, he can begin re-applying stacks to his target again, but can't proc the stun until the cooldown expires. Then we can add an indicator around a stunned target, just as Nautilus and Udyr received.

Potential problems + re-balance:

Skarner's ultimate has a base damage + bonus damage scaling with how many passive stacks his target has. Implementing the above change would increase his ultimate's damage in almost all cases where he previously stunned his target, making Skarner's damage output more reliable. Because of this increase in reliability, a small decrease in the bonus damage per stack on his ult can be implemented, in order to maintain a neutral power shift in Skarner's kit.