The new field boss Ruin Serpent was revealed in the Genshin Impact 2.5 Special Event Livestream, as a part of the sneak peek into The Chasm. The Chasm will be a new area accessible to Travelers once Version 2.6 drops. According to some leaks, the Ruin Serpent is massive.

As with any and all leaks, none of these are official information and should be taken with a grain of salt. All information is subject to changes.

https://media.discordapp.net/attachments/791659074253094933/945144455349018654/GenshinImpact_hd7jlTbf7F.png?width=941&height=491

This image is circulating in the Genshin Impact leaks community. It seems to be a screenshot from a beta version of the game, seeing as the health gauge of the boss is labeled “BOSS NAME” and Kamisato Ayato is on the party. The Ruin Serpent can be seen on the field next to Jean, and it is multiple times taller than her.

An unofficial translation of the Ruin Serpent's description has also been leaked:

“An ancient, aberrant ruin device. Legends say that it is a heavy machinery used for engineering purposes, left behind by the destroyed nation. The gear-shaped structure of the ‘head' is able to excavate the hardest layers of rock with ease. If this really was the case, borrowing its powers, the great army would have been able to traverse the continent easily via various hidden underground paths.”