[Update: 8/17] We have corrections to issue regarding this story. The $99.99 Season Pass includes all of the content for the first six months, which amounts to 30% off the regular price if purchased separately. Also, development of Age of Empires Online has been taken over by Gas Powered Games. Shacknews regrets the errors.
[Original Story] Age of Empires Online will support a Season Pass system for premium content discounts, Microsoft announced at Gamescom today. The discounts only last for a limited time, though, so it probably won't see you all the way through the lifespan of the free-to-play strategy title.
The discount will get you 30% off all premium content for the first six months, reportedly for $99.99. It stands to reason that as a free-to-play game, Robot Entertainment plans on releasing new premium content for longer than that, but it should give you a nice head-start if you plan on buying a lot of free goodies. The company also announced that if you buy the Greek and Egyptian civilizations, you'll get the Defense of Crete Booster Pack for free.
So far we know the pricing structure for only a few of the announced packs: 2 Premium Civilization Packs ($20 each), Pro Packs ($20 each), the Defense of Crete Booster Pack ($9.99), and Empire Extras ($4.99). Buying Greek, Egyptian, and the Extras would cost you $44.99 in total, with Defense of Crete thrown on for good measure. With the Season Pass, that cost would be reduced to just over $30, so gauge your interest in the pricey Season Pass by how much you'll save.