Armello

The hardest part for this achievement is becoming corrupted (rot level 5) early in the game. It really depends on luck because you need nearby Bane's, cards with rot penalties, or perils with rot lose conditions.

Start the game by intentionally losing to Bane's. You can do this by using damage cards on yourself before a fight or burning useless cards during a fight so that you lose dice. You gain one rot each time a Bane kills you. You can also gain rot by using rot cards or losing to rot perils intentionally. Spells seem to have the most rot cards.

Once you real rot level 5 you become corrupted which means killing a Bane or corrupted creature will give you 1 rot level as well. When you fight other corrupted creatures, it becomes a rot battle. The creature with the highest rot gains one die for each level of rot the other creature has. This means that once you get to rot level 6 or so, Bane's become super easy to kill.

Now just continue farming Bane's and rot cards until you reach rot level 13. This is also sets you up for a rot victory. Just get a higher rot level than the king and fight him. You'll get around 8 dice. Just be sure to survive the fight with him. If you die it becomes a regular prestige victory for whoever ever has the most prestige (not you since you just attacked the king).