Hope they give you plenty of missiles.
http://www.nintendoworldreport.com/news/60121/boss-rush-mode-now-live-in-metroid-dread
The second part of Metroid Dread's update revealed in February is now live.
An update has just dropped that introduces the Boss Rush mode. The mode requires completion of the main game, and is a race against the clock to see how fast all of the game's bosses can be brought down.
It does not appear that difficulty level matters for unlocking the mode.
