Ruby-polished Drill Engine

 is a Drill Engine that can be obtained from forging in The Forge in the Dwarven Mines. It increases Drills' by  and  by  (secret bonus). It is the upgraded form of Mithril-Plated Drill Engine.

Obtaining
The Ruby-polished Drill Engine can be forged once the player has reached Heart of the Mountain Tier 5. It takes 20 hours to forge.