Sort all prepared spells by level in a separate pop up UI.
So many things could be done like this. They could have a pop up for :
- Cantrips, spells 1-9
- Innate & Class Abilities
- Consumables
- Thrown
- Tools
- Available Bonus Actions
These could then be sorted by category or name, or pinned to the screen if the player wanted them to be. And the good thing is they only need to be on screen if they have any sub-buttons. Don't have any thrown items? No button! Don't have any bonus actions for some reason? No button! Only have 1 potion left? Well that IS your consumable button! Until you get more, that is.
