One of my players asked me during our session "can my character (Cleric of Moradin) use Defender on himself?"
If not, why not? Is Defender not quite unbalanced? If he faces one monster, the cleric can simple block the cave passage and dodge, giving him AC 20. The monster would have to roll twice every time to try to hit the cleric because of Defender, which would result in a player doing nothing but dodging to ensure that the other players can take down creatures with ranged attacks. If he can’t use Defender on himself, he can simple stand behind the fighter who dodges and thus has AC 19, still forcing the attacker to do two attacks and thus blocking the way while the other players take down the monster. However, if there are lots of monsters, like a dozen goblins, then Defender is practically useless, since it requires that you target a goblin before it attacks, and if that goblin misses then the ability was wasted. We haven’t found a solution to this yet though and will keep testing it hoping to find a creative suggestion.