Monster Hunter: Worlds 4.0 update introduces another new creature to the roster, and the highlight of the new patch is a new monster to hunt. Hunters can now sharpen their blades and track down the Elder Dragon known as Lunastra. The blue beast is a companion to Teostra, the flaming lion many Hunters have already encountered on their way through the campaign.
Source: N4G PC Monster Hunter: World: How to defeat Lunastra and get the most out of the 4.0 update