Ordeal 5 is the final stage in the Disgaea 2: Cursed Memories Cave of Ordeals. It is an unusual stage that requires a bare minimum of 3 Iron Knights (or other characters with 6 throwing) and one character with a throwing distance of at least 3 to complete, in addition to one or more high-level fighting characters and the ability to move extremely quickly. The stage consists of a battle against 11 Sinners of various levels, each equipped with a fist and a belt, followed by a series of long throws (which become No Entry panels on Turn 4 thanks to a walking Geo Crystal, causing the stage to become unwinnable if you don't have a character on the other side by then), and finally a fight against a level 1000 Zombie King (which appears not to spawn on subsequent revisits to the stage, removing the time limit - the geo crystal remains, however) which is always equipped with a legendary Arcadia.
It is possible to attack the Zombie King from the high ground, next to the Geo Panel, if you have an attack with a relatively high vertical range. From this position, it will not be able to hit you.