With the appearance of Aatrox, an interesting theory arose about him not being a character holding his sword, but simply being a living weapon in his own right. This is confirmed by Eduard, who mentions future projects. At the moment, the only Darkin in the game is Aatrox, and three other Darkins are known to exist, so it is almost certain that we will see a new Darkin hero in the future.
However, it is time to move on - I have only opened the door to the world of the Vastai, and another explorer will have to cross it. Today I turn my attention to the other creatures of Runeterra that await their turn: those fearsome, living weapons known as Darkini. The warping creatures of all things from the Void. The rare creatures of legend, the Yordles. Their stories cannot be passed over in silence, and I swear I will be the one to tell them. I may be the only person who can do so.
One of the leaks from a year ago talked about a new Darkin hero Raa'Tul. As we know the name of the new hero will start with R, but it is rather to be assumed that if the leak actually turned out to be true Raa'Tul will appear in the future, because the description below completely does not fit the pair revealed yesterday.
Raa'Tul is supposed to be similar to Aatrox (large helmet and epaulettes), and is an ADC using Varus' stolen demonic bow. Under R is supposed to have an escape (something like Galio's current ult). Along with Aatrox, they are supposed to get the Wargod skin. The leaked hero was supposed to be released in 2016.
Another possibility is that the hero will be revamped because he wasn't satisfying enough. The new character may be named Raa'Tul, except that he will no longer be Darkin, but Vastaj. The new characters could be named Raa and Tul, but there are probably too many of these theories...