The Steam Centurion, also referred to as the Dwemer Robot is a unique enemy encountered at the end of the Dwarven Mines. The Centurion is arguably one of the most powerful enemies in the game, next to Nafaalilargus.
The Steam Centurion will kill Cyrus instantly should it manage to hit him. It takes 5 - 6 regular hits (3 - 4 with a strength potion) to bring down, and can only be fully killed by attacking it's "Achilles" heel, the back of it's left foot.
Erasmo requires a Dwarven Gear to complete the repairs to the observatory and sends Cyrus to retrieve one from the Dwarven mines. After killing the Centurion at the end, looting it's body will provide the required gear.