the way we do multi-ways locally is that most any card that doesn't target (Mirror Force, Lightning Vortex, ...) affects the ENTIRE field, so a well-timed play can literally wipe the field of monsters. We don't really gang up on one person, unless they become annoying or are a threat to win the whole thing with something like Exodia or Final Countdown.

Anyway, I started this build around Morphing Jar #2, since it will basically reset the entire field with it's effect, then I expanded it into a Megarock deck, perfect for the way our multi-ways tend to go.

Monsters(22)
Golem Sentry x3
Legendary Jujitsu Master x2
Megarock Dragon x2
Medusa Worm x3
Exiled Force x2
Morphing Jar #2 x2
Guardian Sphinx x2
Sand Moth x2
Labyrinth Wall
Granmarg the Rock Monarch
Sangan
Needle Worm

Spells(17)
Heavy Storm
Chaos End x2
Mystik Wok x2
Soul Release x2
Giant Trunade
Creature Swap x2
Lightning Vortex
Chain Strike x2
Poison of the Old Man x2
The Shallow Grave
MST

Traps(4)
Dust Tornado
Ceasefire
Jar of Greed x2