In 2008, the band was writing/recording an album with their long-time friend and producer Terry Date. The album would eventually be titled "Eros", and was tentatively set for release on January 2009 (source: Kerrang!). During the sessions, bassist Chi Cheng (RIP) had written on a blog post that one of the songs, called "Trempest", featured the oldschool "fuck you I hope you die" kind of aggression found on earlier Deftones music.
In November 2008, after playing a couple of shows, including two where they played "Melanie" (suspected to appear on "Eros"), Chi had a car crash without wearing a seatbelt. The accident put him in a coma which, despite its evolution and much positive speculation and care, led to his death in 2013, following several infections and one last pneumonia.
Since the accident in 2008, "Eros" was shelved and never touched again. Since then, the band has been asked only too many times what would happen with "Eros", even while promoting the records that followed.
For the latest, in 2020, Chino said it was "halfway done with a lot of vocals missing", Abe said it was halfway finished and they were considering releasing the finished tracks as an EP, Stephen said it was "instrumentally complete".
Below you can find all the material that was made available in relation to the album. Before that, you can watch an almost-complete introduction to the album, made by YouTube user Lie Likes Music
https://www.youtube.com/watch?v=GAFWxf5Xo50Artwork used on their website during the album process, suspected to be the actual artwork

In-studio videos, posted on deftones.com as a promotion move
Deftones eros in Studio 2008 clip 1Deftines eros in studio 2008 Clip 2Deftones eros in studio 2008 clip 3Deftones eros in studio 2008 clip 4https://www.youtube.com/watch?v=vyH1v7RF5H4On January 14, 2008, Chino posted a demo called "You've Seen The Butcher" on Deftones' MySpace. The demo has nothing to do with "You've Seen the Butcher" on "Diamond Eyes"
https://www.youtube.com/watch?v=JWU7snh5vCwLater in 2008, the band played "Melanie" live twice
https://www.youtube.com/watch?v=8v1vijErZvshttps://www.youtube.com/watch?v=j4Qo6EK3AaIOn April 13, 2014 (I think, one year after Chi's death), Chino leaked "Smile" on YouTube. This is a reupload of his original upload, which featured the lyrics to the song
https://www.youtube.com/watch?v=GB0lGKJXFMgIn 2015, a YouTube channel called JG Productions leaked a studio video of the Eros sessions, containing a full audio instrumental rehearsal of one of the songs they were working on at the time. Fans have referred to it as "Dallas" as this song name was in the tentative song titles the band had come up with, however the band never confirmed or denied this song being called "Dallas", it's speculation. This is a reupload
https://www.youtube.com/watch?v=oKcK0-L_AbAHere is an extended and EQ'd version of "Dallas", made and provided by YouTube user youwouldknow:
https://www.youtube.com/watch?v=Fpfu3NfKNHAIn 2019, the band played "Smile" live
https://www.youtube.com/watch?v=gRKWcjka7BwIn 2020, Abe announced the band considered releasing some "Eros" tracks as an EP, while Stephen said it was "instrumentally complete" and Chino said it was "halfway done with lots of vocals missing".