The Key to Evil

The Key to Evil (Japanese (Katakana): 発動！XXモード！！) is the eighteenth episode of Tenkai Knights. It first aired on January 05, 2014 on Teletoon in Canada.

Plot
Beni meets with Guren and the other boys just as school gets out. Guren introduces her to the others and she tells him she wants to show him something. She takes them to the docks and reveals that she'd tricked them. The boys are temporarily rendered unconscious. When they wake up, they realize they'd been transported to Quarton.

Another Guardian, calling himself Eurus, appears before them and tells them that they are about to take a test. The Knights have to battle evil clones of themselves created by Guardian Eurus. Meanwhile on Earth, Gen begins to get suspicious of Mr. White.

The Knights manage to Titan Fusion and Bravenwolf and Tributon destroy all the clones. Beni is surprised that the boys won and realizes she shouldn't underestimate them. Later, Gen, as Dromus, and Eurus meet and talk about how to use the Tenkai Knights' Titan Fusion to find the Black Key. While Gen is suspicious of Eurus's motives, the Guardian claims to be helping Gen to keep balance because Boreas is helping the other Knights.

In the episode

 * Guardian Eurus appears before the Tenkai Knights for the first time.
 * It appears Guardian Eurus is the one who gave Gen and Beni their cores and is responsible for their being on Quarton, like the boys and Guardian Boreas, but that is not confirmed.
 * The Knights (Bravenwolf and Tributon) unlock and use Titan Fusion for the first time.
 * Titan fusion is first introduced in this episode.
 * The knights are given evil clones of themselves possibly created by Guardian Eurus.
 * Beni transports the Tenkai Knights to Quarton, This is unknown how she received this power possibly by Guaridan Eurus himself.
 * Guardian Boreas states in this episode that the new mode the knights have made this titan fusion is a threat to the balance of tenkai energy which means why the knights don't use titan fusion no more in other episodes.