Sunless Sea captain. I stand outside in the sun and wait for him to spontaneously combust or go mad from its radiance.
If I have to fight him in the Neath, I spend my week learning to use a gun and hope, I guess. He's a good fighter, but I might get lucky.
If he's the size of an actual bug, then yeah, you step on him. Might scorch your feet a bit with his spells.
If he's you-sized, forget about it. You're basically fighting a Dark Souls protagonist.