Where to spoil Metal Hardener

8 monsters drop Metal Hardener on spoil, the lowest level is 15. The chance already assumes solo spoiling with no level-difference penalty: put your own level into the calculator.

MobLvlSpoilsWhere
Obsidian Golem Obsidian Golem 15 Metal Hardener · chance 0.83% · 1 pcs Western Mining Zone, Mountain Ridge
Dark Terror Dark Terror 16 Metal Hardener · chance 0.71% · 1 pcs Elven Fortress, Neutral Waters
Enku Orc Shaman Enku Orc Shaman 20 Metal Hardener · chance 0.99% · 1 pcs Dion Hills, Dion Territory
Maille Lizardman Maille Lizardman 22 Metal Hardener · chance 0.58% · 1 pcs Maille Lizardman Barracks
Underground Kobold Warrior Underground Kobold Warrior 27 Metal Hardener · chance 1.22% · 1 pcs Mithril Mines
Hatu Crimson Bear Hatu Crimson Bear 38 Metal Hardener · chance 1.41% · 1 pcs Beehive
Timak Orc Troop Warrior Timak Orc Troop Warrior 43 Metal Hardener · chance 5.77% · 1 pcs Timak Outpost, Oren Territory
Messenger Angel Messenger Angel 70 Metal Hardener · chance 87.58% · 1 pcs Tower of Insolence: Floor 7

What it pays and what is better to kill at your level — in the spot finder.