The first expansion for Diablo III has proven itself to be a huge success for Blizzard, selling 2.7 million copies in its first week on sale. On top of that, players have killed the expansion’s final boss, Malthael, 1.5 million times since launch. The game has also been popular on Twitch.tv, with over 2.5 million views of Reaper of Souls-related streams on the site.

“With Reaper of Souls, we wanted to emphasize all the things that Diablo gamers have always loved about the series, from the dark gothic setting to the piles and piles of epic loot. We’re excited to see that players are enjoying the changes we’ve made to the game, and we look forward to achieving our Paragon levels alongside everyone else in the weeks and months ahead,” said Blizzard CEO Mike Morhaime today.

Reaper of Souls is yet to launch in some major territories however, including Russia, Mexico, Chile and Brazil, where it launches on April 15. In the meantime, an enterprising Reddit user has posted the maths behind the Wizard’s Black Hole spell, determining that the black hole created by the spell is four times the size of an atom, based on how it behaves in the game.

UPDATE 5/4: To celebrate the new sales figures, Blizzard have announced a 50% bonus XP weekend.