Information from the design group
https://www.youtube.com/watch?v=Y61WCCW_IGI
From a short paragraph introducing the quality of season 7, the design team revealed the appearance of Illaoi and “dragons”. From here, it is possible to speculate that the quality of the 7th season will take the topic of “dragon”.
Similar to Garen and Darius of Season 5, Illaoi will be the “last boss” with appearance and skill set made according to the theme “Dragon”. Riot also refers to different factions and each side will have their own tycoons (Illaoi will be one of the tycoons).

A new mechanism similar to the technology core
Riot is designing a completely new mechanism. Although there is no detailed information, Riot also noted that this mechanism will feel similar to the technology core of season 6.
Dark mechanism returns?

CLUME players from season 5 will no longer be strange with the dark mechanism that has been storming for a while. Now, at Season 7, Riot will bring back to one mechanism in another shape, but still allow players to choose the equipped ingredient at a fixed time. According to the Stephen “Mortdog” Mortimer game design director, the dark mechanism will return, but in a better way.
Information about generals
China is quite special when theCC is running in a completely separate interface from the League of Legends. Because of this, some people have found leaked information about the quality of Season 7.
Although this information may be accurate, nothing guarantee they will be kept until the quality of Season 7 officially launched. In the video below, we can see that these generals will appear in theCC Season 7:
https://www.youtube.com/watch?v=9J8istnzyz4
Brand
Kai'sa
Karma
Lee Sin
SETT
Thresh
Volibear
Yasuo
Message
The last thing we can know at the present time is an extremely confusing message from Mortdog: “There will be some” big changes “that we show us (how to develop the quality of the quality from Riot)” how you respect “you. Remember this message.”