Obtain the Fragile Strength charm from Leg Eater in the Fungal Wastes
Defeat the boss in the Colosseum of Fools to earn enough Geo if needed
Bring Fragile Strength to Divine in Dirtmouth after unlocking the Grimm Troupe
Pay Divine to upgrade Fragile Strength into Unbreakable Strength
Use Unbreakable Strength to increase nail damage without breaking on death