For Slag-Licked, you need to deal the Slag status effect to enemies, then deal damage to them while they are Slagged. When enemies are Slagged, you deal extra damage to them, except for other Slag weapons, so it is best to switch to another gun.
- Rank 1: Deal 5,000 bonus damage to Slagged enemies
- Rank 2: Deal 25,000 bonus damage to Slagged enemies
- Rank 3: Deal 150,000 bonus damage to Slagged enemies
- Rank 4: Deal 1,000,000 bonus damage to Slagged enemies
- Rank 5: Deal 5,000,000 bonus damage to Slagged enemies