SPOILER ALERT: This article contains spoilers for "Avengers: Endgame Encore," now playing in theaters.

Marvel has re-released "Avengers: Endgame" in theaters as "Avengers: Endgame Encore," a slightly longer version of the 2019 blockbuster with four minutes of new footage tying directly into "Avengers: Doomsday," which opens Dec. 18. The added scenes feature Robert Downey Jr.'s Doctor Doom, Tom Hiddleston's Loki and Mark Ruffalo's Bruce Banner.

The new scenes were shot during "Doomsday" production and inserted into the re-release to bridge the two massive "Avengers" stories. Marvel has been building hype for "Doomsday" for a full year, starting with four short teasers attached to last year's "Avatar: Fire and Ash." Those teasers revealed that Steve Rogers (Chris Evans) and Peggy Carter (Hayley Atwell) have a son; focused on Thor (Chris Hemsworth) and his adopted daughter; showed Prof. Xavier (Patrick Stewart), Magneto (Ian McKellen) and Cyclops (James Marsden) from Fox's "X-Men" universe crossing into the MCU; and brought together Black Panther (Letitia Wright) and the Wakandans with the Fantastic Four.

The first new scene arrives during Steve and Peggy's dance in the closing moments of "Endgame." Steve has hung up his Captain America costume, passed the shield to Sam Wilson (Anthony Mackie) and settled down with Peggy after traveling back in time. Now they get a knock at the door from Loki. The reformed trickster last appeared in the finale of "Loki" Season 2, resigned to holding up the entire multiverse for the rest of time. Here, in his Time Variance Authority uniform, he pays the couple a visit — perhaps to discuss the unstable branch Steve's time travel created in the multiverse.

A second scene takes place at the Time Variance Authority with Mobius (Owen Wilson), Casey (Eugene Cordero), Ouroboros (Ke Huy Quan) and Miss Minutes (Tara Strong). They watch two Earths begin to collide in an incursion and fire on each other. More alternate worlds start colliding and terminating. The entire multiverse is collapsing. Those two Earths could be Fox's "X-Men" universe and the mainline MCU world — especially since Prof. Xavier, Magneto, Cyclops, Mystique (Rebecca Romijn), Nightcrawler (Alan Cumming) and Gambit (Channing Tatum) are already set to cross into the MCU, potentially setting up their clash with the Avengers teased in the "Doomsday" trailer.

A third scene appears during the credits and takes place after Bruce's apprehension in "Spider-Man: Brand New Day." In this summer's record-breaking blockbuster, Bruce loses control and transforms into the Hulk when Jean Grey (Sadie Sink) controls his mind. Spider-Man (Tom Holland) defeats him, and Bruce is taken to a secure medical facility. In the new credits scene, Bruce tinkers on a serum in an underground bunker to suppress his transformations. Doctor Doom breaks into the facility, Bruce turns into the roaring Hulk to face him — and the scene cuts away. Whether Bruce or the Hulk reappears in "Doomsday," and under whose control, remains open.

The final scene comes at the very end of the credits. The original "Endgame" closed with a mysterious metal-clanging sound, which diehard fans identified as Tony Stark forging his armor in "Iron Man." Now viewers see flashes of Doctor Doom making his metal mask to the same sound. The dark twist suggests Doom and Iron Man — both played by Downey Jr. — may have mirrored origins.

"Avengers: Doomsday" opens Dec. 18, the same day as "Dune: Part 3," setting up a "Dunesday" showdown at the box office. With the new scenes, advance teasers and a year-long countdown clock, Marvel and Disney are betting "Doomsday" becomes another smash hit on the heels of "Spider-Man: Brand New Day's" record-setting run.