Wild Arms 2
Illsveil Prison is the independent prison island to which convicts from any nation in Filgaia can be sent. The warden of the prison is a prisoner himself. Irving frames Ashley, claiming he tried to attack him, and orders the guards and Lilka to escort him to Illsveil as punishment. While Lilka gathers Ashley's things to help him break out of the prison, an escape is already happening in another part of the prison. This escape, as it turns out, is headed by Odessa.
Ashley and Lilka find Brad in his cell and find it odd that he's not escaping while everyone else is. It becomes clear that he was waiting for them, and that Irving had tricked Ashley and Lilka instead of trusting them with the assignment.
Wild Arms 4
Illsveil acts as the final dungeon of Wild Arms 4. The party reaches this level just after witnessing the death of Gawn Brawdia, who gave his life protecting their craft from 11 missles launched at them from Lambda, who just happened to be on Illsveil. The player must face many puzzles, monsters known as Wild ARMs, and the final few bosses of the game, Farmel, Lambda, and Hauser, the ultimate final boss, having merged with the Divine Weapon.