The key mechanic in that set was called Horsemanship. Honestly, Horsemanship might as well say unable to be blocked, because only other creatures with Horsemanship can block a creature with that ability. There are only a few creatures in the game with that mechanic, and all are from that set. Sun Quan, Lord of Wu is the other creature well-known for Horsemanship. His ability gives ALL of your creatures Horsemanship, which is pretty fantastic.
Lu Xun is a bit less exciting than Sun Quan, but his effect is very useful. Whenever he deals damage to an opponent, you may draw a card. Now, his ability is not limited only to combat damage. If you were to find a way to have Lu Xun deal damage to an opponent, say with an Equipment that causes target creature to deal 1 damage to a target player, you would still draw a card.
Obviously, card draw is awesome to have in any deck, so Lu Xun can fit into a lot of Blue decks with ease. Since becoming available in the Commander 2013 product, Evasive Maneuvers, players only need pay about a dollar per copy for him now. Previously, you would need to shell out over $20 for a single copy of him. Now that he’s more accessible, it’s a lot easier to see him fitting into a lot more budget lists.
Also, Lu Xun, Scholar General is a Legendary Creature, meaning that he is a potential Commander. While he’s probably nowhere as good as Sun Quan as a Commander, the fact that he can be a consistent draw engine that oftentimes can’t be blocked means he can be a surprisingly decent Voltron-style commander. Any abilities that can give him double strike allow you to draw two cards instead of one.
A deck built around him could be a more fair version of Azami, Lady of Scrolls – a Commander which allows for such a ridiculous draw engine that it hits its win conditions more often that not. He may be only a casual sort of Commander. But it's interesting to consider what sort of draw-based shenanigans could be made with him at the helm. If you'd like, EDHREC, the premier EDH decklist website, has a few suggestions for building a Lu Xun EDH deck.