Speaking of the auction house, it seems Aion will feature both an auction house system and a personal store system. I asked about the crafting system and was basically told to not expect a reinvention of the wheel here. They're going with a pretty typical trade skill system in Aion, so if you've crafted in an MMO you probably know what to expect here. Recipes will apparently come with both skillups and as dropped loot items. The in game mail system does have one really neat feature, or at least I thought so. You can pay slightly more for "express delivery" when shipping some items to a friend. Which basically means, if you're out raiding a dungeon or something really far from civilization, you can send out a plea over your guild chat or through a tell to a friend, who can then buy you some potions and have them delivered directly to you. Very handy, I can't count how many times I've had to run back to town for potions or such in a game only to get back and find the area I was in had respawned or someone else had moved in and was camping it. Ever been in a game and found an extremely cool looking set of armor, but the stats/bonuses on it weren't as nice as the crappy looking stuff you're wearing? Well, consider that problem solved in Aion. It seems you will have the ability to 'combine' two different sets of armor, making the one you want to wear for its bonuses look like the one you want to wear for its appearance. And forget a simple dye system; in Aion you'll be able to add particle effects to your gear. There will also be a system in place for uploading your own custom guild emblem, which will be displayed in various places on your character for showing off your guild allegiance. The guild system itself seems fairly typical of MMOs and there will be an alliance system for grouping multiple like-minded guilds together.
Combat in Aion seemed very fast paced and fun when I was playing it. There is an extensive combo system in the game with a lot of branching paths. Combos will trigger both reactive and passive effects. Some will lead up to more powerful attacks; others will trigger buffs, etc.
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Resource: MMORPG.com