According to a video posted by YouTuber Zullie the Witch, Elden Ring has been hiding a 7-year old mystery boss from Dark Souls 3 all along. In previous Soulsborne games, data miners had unearthed some unused content such as audio, bosses, and even animations. And now, data miners have discovered something in Elden Ring.
Zullie found out that the Ulcerated Tree Spirit was originally a boss in Dark Souls 3 which never came to light. A file was found in the data folders of Dark Souls 3 named “SnakeSoul” which actually did not have any connections to any of the bosses but only with Pus of Man.
It could all be a coincidence since the name could be anything, but things take a turn when Zullie shows that the early Dark Souls 3 videos reveals what appears to be a shadow of a boss that looks strikingly similar to the Ulcerated Tree Spirit.
This is sufficient evidence to conclude that the boss was indeed transferred from Dark Souls 3 to Elden Ring. This also puts an end to the 7-year-long mystery.