So the other day I suddenly had an idea to possibly improve Nimbus cloak, I personally love using Nimbus cloak on some of the champions I enjoy to play but there are other champions where it does not seem that reliable. I know that not everyone rune has to be reliable on every champion, since that isn't really possible but what I thought of could possibly fix its main issue. Champions with shorter cooldowns on their ults cannot use Nimbus cloak reliably, Neither is it useful on champions with longer ult cooldowns. Some champions, for example Anivia could actually very well use the extra movement speed to catch an opponent off guard and suddenly with their ult catch them because of the added movement speed and slow from the ult.
**The possible change:**
I was thinking that Nimbus cloak could introduce a sort of stacking system, for every X amount of time you haven't used your ult, also seen as, haven't triggered the rune effect, it stacks up till a maximum, on that Maximum it could give more movement speed than it does now, but if it is used beforehand, lets say after 60 seconds it gives around the same movement speed as now, all the way down to some of the lowest ult cooldowns, where it wouldn't give anything noticable, maybe 1ms, on the other hand after 120s it could give more movement speed. This could add a sort of playstyle with the rune, similar to people who use phase rush, to sometimes hold on to your ult a bit longer to get that extra engage speed, with champions with shorter cooldowns it could actually be used for slightly less movement speed, or you could hold off on using your ult a bit longer to get the extra movement it gives.
To me it seems like a good idea for champions like Diana who, as it seems to me at least, cannot use Nimbus cloak that reliably at the moment, because using your ult puts it on a cooldown, which then means u cannot even use the Rune during the next X amount of time, whereas if a change like this was made, you could lose the stacks, sure but you could still get a minor speed boost the next ult you do. I know that its not a big change, and possibly could be a bit useless in a way, so let me know what you think.