Havoc has been printed in
Tempest,
and has 12 combos.
Havoc Festival + Archfiend of Despair
Combo result
Massive damage to opponents. Almost assured win. Prerequisites
All permanents on the battlefield.
Havoc Festival + Wound Reflection
Combo result
Damage equal to each opponents life total to them. Prerequisites
All permanents on the battlefield.
Magmatic Galleon + Havoc Jester
Combo result
Infinite colored mana. Prerequisites
All permanents on the battlefield. An opponent controls an indestructible creature, or you have a way to give an opponent's creature indestructible. You control a number of Treasure tokens greater than the indestructible creature's toughness.