DOOMSDAY CAGE
First held in Supreme Championship Wrestling, the Doomsday Cage has been constructed annually in the PWF, as well. A three-tier cage is built over the ring, with hatches designed to allow competitors to move between the cages. In a one-on-one encounter, the superstars begin in the top cage and are able to move around the cages as they see fit, with victory coming by pinfall or submission on any level of the structure. A special elimination version of the Doomsday Cage match was used in the SCW, with four men in each cage, and the final survivor of each battle facing off in a final encounter.

For more:
History of the Doomsday Cage