Lindworm is the boss on the rooftop of Castle Nex.
This is one of the most intense fights you'll ever have to face, so make sure you are stocked up on healing potions, you've used all your crystal flowers to boost your stats and so on.

Lindworm casts several waves of enemies at you. During the enemy waves, he has a shield that makes him immune to all damage. So kill the other enemies first, but save your special attacks for him. Kill him as fast as possible because the longer he lives, the more waves of enemies he throws at you.

He will also keep taunting you by text shown on screen.

Hitpoints: 3000

Drops: 1 power gem. His enemy waves also drop regular items.