Yavimaya, Cradle of Growth, Life and Limb, and Plague Engineer

Prerequisites

• Yavimaya, Cradle of Growth on the battlefield
• Life and Limb on the battlefield
• Plague Engineer on the battlefield
• "Saproling" chosen with Plague Engineer

Steps

1. Yavimaya causes all lands to be Forests in addition to their other types, thus Life and Limb causes all lands to be 1/1 Saproling creatures
2. Because Plague Engineer gives all Saprolings your opponents control -1/-1, they die as a state-based action due to having zero toughness
3. Whenever an opponent plays a land, it will also die as a state-based action

Results

• Destroy all lands opponents control
• Destroy any land that enters the battlefield under an opponent's control