Bronze Defender

Magical Resistance- The Bronze Guardian has advantage against saving throws caused by spell effects. 

Vigilant- the Bronze Guardian cannot be surprised. 

Multiattack. The armor makes two melee attacks.

Slash. Melee Weapon Attack: +7 to hit, reach 10 ft., one target. Hit: 5 (1d8 + 4) slashing damage.

If the Bronze Guardian takes 20 or more points of damage on a single turn, then it can channel the magics of it's circle to heal 3d10 damage. However, it will not be able to take circle actions until the start of its next turn.

Magnetic circle. During each round of combat the Bronze Guardian can either-

Attract Metal- all metal weapons and armour are attracted to the circle of the Bronze Guardian. Any PC holding a metal weapon or wearing metal armour must succeed on a DC 14 Strength saving throw or be dragged up to 15 feet directly toward the Bronze Guardian. PCs wearing metal armour make this save at disadvantage. A character can choose to let go of their weapon instead of making the save. 

Repel Metal- all metal weapons and armour are repelled by the circle, shoving them 15 feet directly away from the Bronze Guardian.  Any PC holding a metal weapon or wearing metal armour must succeed on a DC 14 Strength saving throw or be thrown 15 feet directly away from the Bronze Guardian, taking 1d10 bludgeoning damage and falling prone. PCs wearing metal armour make this save at disadvantage. A character can choose to let go of their weapon instead of making the save.