In my opinion, Shield is one of the strongest spells in all of fifth edition. For a level 1 spell slot and your reaction, it grants you +5 AC for a whole round, and since you cast it after you know you've been hit, it's not wasted unless the roll beats your AC by 5 or more. In the campaign I play, we have 3 people with 18 or more armor class and 4 slots of Shield, and it basically amounts to dodging four hits (and being almost invulnerable for the remainder of those rounds) per long rest. So I propose to change Shield's casting time to:
One reaction, which you take when you are targeted by an attack or by magic missile.
This means that when an enemy attacks you, you have to choose whether to cast shield or not before you see what they roll. This means that the spell could be wasted if the attack would have missed anyways, and it makes it harder to guess what the enemy's attack bonus might be.
One reaction, which you take when you are targeted by an attack or by magic missile.
This means that when an enemy attacks you, you have to choose whether to cast shield or not before you see what they roll. This means that the spell could be wasted if the attack would have missed anyways, and it makes it harder to guess what the enemy's attack bonus might be.