A player with an invincible build is effectively immortal and unable to take damage. Players enjoy trying to create an invincible build while playing in endless mode, as the true test of their buildcrafting is the ability to create a build so powerful they can simply put down the controller and walk away and never die. Some game design philosophy encourages this, other games are made so this is not possible. But survivors-like fans seem to prefer the possibility. See also: Broken.