That darkness you entered... that's certainly where it lives. As you no doubt surmised, your mind, to say nothing of your fleshy mortal meatsuit, cannot withstand the aura of dread that surrounds this monster. Luckily, my superlative foresight and ability to cultivate positive working relationships with a wide variety of talented individuals means that I have a solution that will allow you to get close enough to that beast to kill it.