Fans have found assets for future map changes for Summoner's Rift for League of Legends in the archives.
The map is called "Ruined King" and will be part of a new temporary mode with the current title of "Ult Book". No more details on the game mode or the dates it will be live are available, but the only Dragon on the map is the Infernal Dragon.
Although little details on the actual game are there, it seems a lot of the assets are available.
The thread on Twitter by Ascaryan shows different parts of Summoner's Rift as well as some different assets, including a new model for Baron Nashor and Dragon.
Although the Baron Pit doesn't look quite complete, the Dragon model looks reminiscent of that old Mordekaiser passive, or more likely the Ruined Dragon which can be found in Teamfight Tactics .
It seems that the map has been given an eerie look, with plenty of ghostly greens and blues to match the Ruination theme.
To round it out, there is a loading screen which shows the Mist advancing over Runeterra, as well as two unidentified assets. A guess would be that these are a new look for minions or Towers.
League of Legends is partway through the Ruination story, and thoughts are that it will continue from July 14th as that is when an event is due to start on Legends of Runeterra.