If you want to pick up Dead Cells DLC, but you can only choose one, this should be it. It adds one (rather inconsequential) area and two of the best boss fights in all of Dead Cells. The Lighthouse fight is one of the most insane sequences I've ever seen in an action platformer, and the fight atop it is an alternative final boss to the game, which is also stunning and helps break the tedium of the Boss Cell grind. These are much, much harder than the default paths to the end of the game, however, so you might as well not.