darksiders
The Tree of Life is a gateway. From it, one may travel to places undreamed of. Whether of oceans and forests, or ice, or endless night... the Tree exists there. It may appear different, yet it is the same Tree and its roots connect all the Realms. The Tree of Life is not where journeys end, but where they begin.
Elder Eideard, on the Tree of Life.

The Tree of Life and Death is a massive tree that links the realms of the Darksiders universe. Each realm has its "own" tree, in the darker realms it is the Tree of Death while in the realms of light, the Tree of Life. In truth, there is but one tree that manifests itself in a different form, reflecting the inherent duality of being. The Shadow Lands exist in a blighted space between the opposing incarnations of the Tree. In any incarnation, the gate to the Well of Souls is embedded in its trunk, the path by which spirits of the dead find their way to the Kingdom of the Dead and to other realms when they are reborn. It can be used to travels to another realm/reality.

Darksiders II

The Tree serves both as a method of transportation and a critical plot element in Darksiders II. After helping the Maker's restore the Guardian and cleanse the Forge Lands, Death uses the Tree to traverse the realms in his quest to redeem his brother by reviving humanity. After acquiring the two halves of the Key to the Well of Souls, Death opened the massive gate in the Tree's trunk to access the well.

Inside, the horseman did battle with the root of Corruption, Absalom, and ultimately cast himself into the Well upon his victory, sacrificing his own life and the souls of the Nephilim to revive humanity.

Trivia