https://www.gamespot.com/articles/monster-hunter-world-update-adds-new-elder-dragon-/1100-6459317/

Monster Hunter World's 4.0 update is now available on PS4 and Xbox One. The patch, which weighs in at approximately 550 MB on Sony's console and 570 MB on Microsoft's, makes a long list of bug fixes and changes to the game, along with introducing a fearsome new monster to hunt.

The biggest addition to the game is Lunastra, a returning Elder Dragon from the series' 2006 installment, Monster Hunter 2. Known as the "Empress of Flame," Lunastra is the female counterpart of Teostra. She can unleash powerful attacks with her mate, and Capcom says her "capacity to alter the environment around her is unmatched."