By unusable I mean not equip-able in the inventory. I can use "player.IsInCombat" to check if the player is in combat but how do I actually make a particular item not equip-able?

Just give it a script with an OnEquip block that unequips it if the player's in combat.

But that won't work with consumables, will it?

Be aware that the isincombat check will catch the player if he's in the "Caution" state with an enemy, not just fighting.

I don't believe that consumables can be equipped. If you click them, they.... get consumed.

You could try an onactivate block on your consumable. I've never looked at or tried such a thing. No idea if such a block will run, or if it will work as an intercept point.

Nope, it won't. But the fact it's a consumable makes the whole thing trivial, really- just add an "Isincombat == 0" condition on whatever the effects are, and add another effect with "isincombat == 1" that shows a message saying "Can't do" and adds a copy of the ingestible back.

This is exactly what I was thinking of doing, was just wondering if there was an simpler way. Thanks for the help though