I wish there was a way to queue up commands.
In Heroes of the Storm, you can queue up commands with shift click. For example, you can click to move somewhere, then hold shift and click somewhere else to move there once you reach your first destination.
This is something that most RTS games have, as it's really important to queue up different commands there when multitasking, but it has its place in MOBAs as well, helping you do small optimisations.
For example, you could recall, then hold shift and right click to the location you want to go after recalling, that way, the moment your recall finishes, you already start moving. Currently, if you try to optimise your recall, you will end up just cancelling it half of the time which really sucks. There are many other use cases and niche interactions with specific champions that would be pretty cool imo.