Valve announce the Dark Moon event

From now on, up until February 6th you'll be able to join forces and take part in the highly entertaining Dark Moon event.

The Dark Moon special event kicked off in game yesterday and is largely an entertaining way to enjoy DotA 2 with your friends and teammates. Continuously spawning waves of terrors crash against your defenses, as you protect Selemene’s temple against the Dark Moon Horde and for what, you might ask? Well, one of the possible rewards from participating in this event is the incredibly rare, rather amazing, immortal courier: Dark Moon Baby Roshan. Alongside the chance at this courier are many other rewards, which can be redeemed with the special event points that are earned when playing.

Valve had the following to say in their announcement for the event,

 Survive the evolving assaults to earn special event points, then redeem your points for increasing Dark Moon Rewards. With a Daily Bonus and multiplier available to boost your score, the only limit to earning additional rewards is your devotion to the cause. ”

The event will only be running until February 6^th, which is the Monday after next, meaning you have just under ten days to participate and hope to obtain the courier.

source: DotA 2 blog