If you are not at the end of the game and don't want to be spoiled, don't read on.
After you get the Meteomobile, head to Teusa. Once you land, go in the nearby passage way to the North East. In the next room head South West and interact with the cage on the platform. Soon you'll fight Sasheer. It seems he doesn't have any more HP than the first time you beat him. I used Hoston's gather 5 ability twice and he died.