Animated Armor

Actions

Multiattack. The armor makes two melee attacks.   Slash. Melee Weapon Attack: +4 to hit, reach 5 ft., one target. Hit: 5 (ld6 + 2) slashing damage

Legendary Actions

Autodestrucción. The Animated armor Activates Autodestrucción and on its next turn it explodes doing 8 (2d6 + 2) magic damage to anyone in a 25 ft radius with a 12 saving roll to half damage

This empty steel shell clamors as it moves, heavy plates banging and grinding against one another like the vengeful spirit of a fallen knight. Ponderous but persistent, this magical guardian is almost always a suit of plate armor. To add to its menace, animated armor is frequently enchanted with scripted speech, so the armor can utter warnings, demand passwords, or deliver riddles. Rare suits of animated armor are able to carry on an actual conversation. 

Castles, dungeons, where ever there is a mage or wizard and armors.