Or more precisely, if you can't see the item coming, then you shouldn't be able to dodge it. Maybe you need to be able to see it for a minimum number of moves while it flies through the air (say 3), or be able to see the thrower. This might make for some interesting strategy where you can throw an undodgeable item if you're invisible and close enough, but if you're too far away, it gives the target a chance to dodge.
Or more precisely, if you can't see the item coming, then you shouldn't be able to dodge it. Maybe you need to be able to see it for a minimum number of moves while it flies through the air (say 3), or be able to see the thrower. This might make for some interesting strategy where you can throw an undodgeable item if you're invisible and close enough, but if you're too far away, it gives the target a chance to dodge.