The 'your mind goes numb' message in Terraria signifies the defeat of the first Celestial Pillar. This status message is a way to alert all players to the pillar's destruction, which may have occurred off-screen. The Celestial Pillars are a significant challenge in the game, spawning minions that can deal high amounts of damage and easily swarm the player. There is no set order in which the pillars must be defeated, so 'your mind goes numb' could refer to the defeat of any of the pillars, such as the Stardust Pillar or the Vortex Pillar.