The Highbreed Tree Monster was a failsafe that would be activated in case the Highbreed lost the war on Earth. It was activated by a Highbreed Officer when his hibernation pod accidentally opened up due to an earthquake. It only appeared in If All Else Fails.
The failsafe looks like a giant Highbreed with red eyes covered in trees, soil, and other organic matter. This monster is the size of Way Big.
Rather than having a mind of its own, the monster relies on intelligent beings that it can command through wires. If the wires are cut, it loses control over its "organs". Although better defended than its "antibodies," Ben was able to simply hack its safeguard using Swampfire's control over plants. Without a brain, it shut down and was then able to be destroyed by having a free willed being become the brain and told it to commit suicide.
Ben 10: Alien Force
- If All Else Fails (first appearance; destroyed)