The Ultimate stretch goal of 14 million has been reached and any players who have (or do) purchased a compendium are now entitled to receive all new weather effects for the Dota 2 map. Initially there was no additional stretch goal after the 14 million mark, but with new benchmarks being met as fast as they can make then it looks like there's already a new one in place.

If the compendium is to reach 15 million before the deadline a Special Axe Immortal, Longform Comic will be the reward. While this isn't an ingame reward that seems to be the prime motiveyor of purchases, the gap between 14 million and 15 million has already been bridged halfway. Currently the exact number is hovering around the 14.4 mark, so if you want to get your hands on that comic there's still time.

If you want to keep track of the compendium rewards or purchase one for yourself, head over to the official compendium page.