Wyndham Catacombs

Wyndham Catacombs is built into the eastern foot of Mt. Gelmir. The halls are full of lightning traps, and the lower level is flooded and home to putrid corpses, so watch both the walls and the water.

The boss is an Erdtree Burial Watchdog. Along the way you can pick up the Lightning Scorpion Charm, which boosts lightning attacks.