Blizzard has quietly opened pre-registrations for a Diablo 4 closed beta, allowing players to opt-in for a shot at the closed beta when testing starts. To do so, all you need to do is head to the Diablo 4 website and click a little "Pre-Register" button, then log in to your battle.net account for a chance to get picked as a tester. As of now, no date has been announced for the closed beta.