Rainmaker

Rainmaker is a Ranked Battle mode in Splatoon that was announced in the Splatoon Direct on May 7, 2015 and will be added in a future update. Nintendo has revealed the mode will somehow use the weapon shown above, which appears to be a metallic tiger/fish with a nozzle in its mouth, known in Japan as a Shachihoko.

Recently, it was leaked how this mode will work.

Description
"In Rainmaker, both teams compete to snag the Rainmaker. Once you've got it, the goal is to carry it into the other team's base! So as soon as the battle begins, grab that Rainmaker! It's guarded by a shield, though, so you'll need to bust it out first. Once you snag it, head for the other team's base. And be quick about it! If you run out of time or get splatted, the Rainmaker will be dropped. Its shield will also reactivate. The Rainmaker is crazy heavy, so you can't Super Jump while carrying it. Your teammates will have to watch your back! The Rainmaker can also shoot ink like an Inkzooka, so you can clear a path! The closer you get to the enemy base while holding the Rainmaker, the lower your goal distance will drop. If the battle ends without anyone carrying the Rainmaker to the goal, the team with the lowest goal distance will win!"

- In-game description

Rainmaker is similar to Tower Control in that it requires teams to move a certain object to a point in the other team's base. However, in Rainmaker, only one player may have control of the Rainmaker, and they themselves must control where it goes. The device is encased in a shield similar to a Zapfish's bubble in Octo Valley, and must be freed before it can be captured. It is also capable of shooting twisters of ink like an Inkzooka, allowing the player in control to have a form of defense. Because the Rainmaker is so heavy, the player holding it cannot Super Jump. If it is dropped, a shield will reform around it and it can be recaptured by any other player. The objective of this mode is to carry the Rainmaker into the enemy team's base, decreasing the amount of distance left to travel along the way. If the match ends without a team successfully carrying the Rainmaker to its designated spot, the team with the lowest amount of distance left wins.

Trivia

 * Rainmaker was first announced in the Splatoon Direct on May 7, 2015. However, its description was extremely vague and only a picture of the Rainmaker itself was released.