The Tower of Darkness (Japanese: あくの塔Tower of Evil) is a landmark on the Isle of Armor in the Galarregion. It is one of the Towers of Two Fists, and it is where the player goes during The Isle of Armor Expansion Pass if they wish to evolve their Kubfu into a Single Strike StyleUrshifu. This can be achieved by defeating all the Trainers in the tower and having Kubfu examine the Scroll of Darkness on the top floor. The player is only allowed to enter the tower if Kubfu is the only Pokémon in their party. However, if the player doesn't have Kubfu in their party or Box, they can climb the tower with any Pokémon.
If the player chooses to train Kubfu here, the Tower of Waters becomes inaccessible to them.
The Tower of Darkness appeared in PASS35, where it was spotted by Henry, Casey, and Marvin while they searched for the Rusted Sword and Shield at Challenge Road. The next day, they returned to the tower to search for the artifacts, but were denied entry, due to the tower only being open for those training a Kubfu. Mustard allowed Henry to battle the Master Dojo Student guarding the tower with the Kubfu he had entrusted with him, but Kubfu was quickly defeated by the guard's Impidimp.
The next night, Kubfu returned to the tower to look for the artifacts, but was easily defeated by the Urshifu guarding the tower. The next day, Mustard revealed that the tower had been searched thoroughly following Henry's visit, but no sign of the artifacts was found.
Tower of Darkness was introduced as a Stadium card in the Pokémon Trading Card Game during the English Sword & Shield Series (the Japanese Sword & Shield Era). It was first released in the Japanese Single Strike Master expansion and the English Battle Styles expansion, with artwork by 5ban Graphics. In Japan, it was reprinted as a Holofoil card in the Gengar VMAX High-Class Deck and as a Non Holofoil card in the VMAX Climax subset. It lets players draw 2 cards from their deck, but only if they first discard a Single Strike card from their hand.
Trivia
If Kubfu is holding an Everstone upon interacting with the scroll, Mustard will notice it, and allow the player to not evolve it.