The ability to put more than one skill on the same hotkey.
The way I imagine this working is that it cycles between them. But if one skill is off cooldown and the other isn’t, the one that’s ready takes precedence.
The way I would use this would be to put, e.g., Blood of Dreeg and Word of Renewal on the same button. I want these both at 100% uptime, and either will do when I need an emergency heal. So I don’t really care which one I’m casting, generally. I either want to cast both in sequence, or whichever one is off cooldown.
Could even work for Curse of Frailty and Word of Pain, on my FoI Deceiver, for example. Both are just chaos RR. It’s too difficult in GD anyway to know exactly when they need to be re-applied, so it would be fine to have a button that cycles them, that I could hit every now and again.
I’d even use this on all my Oathkeepers (well except my Vanquisher Templar), for Vire’s Might and movement rune. This is a case where I always just want “whichever one is off cooldown”.
This innovation would save me so, so much hotbar space and greatly improve quality of life for my many Occultists.
Heck, even if it wasn’t smart enough to switch based on readiness/cooldown state, I’d still use it and just press the button twice when I needed to.
I don’t mind piano builds. I prefer them even! But I hate when I have more buttons that fit on keys that I can reach. I remap so that I can reach about a dozen buttons easily, and yet even so I find myself sometimes forced to forego an item-granted skill. I rarely have space to hotkey Aether Cluster (my solution is I mostly just don’t use them).
I’m sure this probably isn’t going to make the cut in terms of priority. But I would love it more than any other improvement to the game.