Adamantine Shield: When a melee attack misses you, the attacker is sent Reeling for 2 turns.
Shield Bash: When a foe hits you with a melee attack, you can use your reaction, to knock it Prone unless they succeed a Dexterity Saving Throw.
Attacker's can't land Critical Hits on the wearer
The dull shine of the adamantine promises this shield could take a thousand beatings - and still look as good as new.
Location - Adamantine Shield