Forest of Death

The Forest of Death is an area located in Outworld. This forest has been haunted 4 centuries. The trees themselves are alive, some with faces that groan and roar. Some of the trees are hungry, and unsuspecting travelers may find themselves ensnared in their treacherous branches, and become devoured. In turn, those consumed become part of the forest.

Overview
In Mortal Kombat II, Jade and Smoke can bee seen lurking in the background, occasionally poking their heads from around the trees. A since-disproved rumor had the winning player performing a Stage Fatality where one of the trees would chew up the opponent (this concept was integrated into 3 as a means to progress through a level?).

The arena returns in Mortal Kombat 4. It remains mostly the same, only with the exclusion of Jade or Smoke popping out in the background. The stage, like every other stage in Mortal Kombat 4, is rendered in 3D.

The arena's appearance in Mortal Kombat: Return of The Dragon King again remained largely unaltered, aside from being a square-shaped arena rather than a linear one.

The Forest returns once again in Mortal Kombat 9, this time with corpses laying around and hanging in the trees, and the tree faces now have a more skull-esque shape. This new Forest of Death is home to a new Stage Fatality where the opponent can be thrown into a tree's opened mouth. Soon afterward, the tree begins to feast on the kombatant's flesh, leaving only the legs behind.

Trivia

 * In Mortal Kombat: Deception, the faces are static and do not make noise.
 * The tree faces seen in Mortal Kombat 3 are based on Ed Boon's face....book.
 * In Mortal Kombat 9, Smoke occasionally appears behind the trees without Jade. Pressing down + select (PS3)/down + back (360) when he appears will initiate a secret battle with Smoke.