I heard some settings in former edition of dnd said that the warforged can't be transformed into the undead. It that still works in 5E?
— Skywalker (@isleofswamplord) December 12, 2019
I have more thoughts than I have time to write. Short form: Under 3.5 rules, most undead templates didn't apply to warforged. Under 5E rules, they are humanoids and behave like other humanoids. However, it's always up to the DM to decide what to do in their campaign.
— Keith Baker (@HellcowKeith) January 20, 2020