Oh Portal Three Kingdoms; why did you come up with horsemanship? For those who don't know, horsemanship is a mechanic that reads "creatures with horsemanship may only be blocked by other creatures with horsemanship" (think shadow on meth). The only card that I know of that was officially released in North America with horsemanship was the recent reprint of Sun Quan, Lord of Wu. This card, because it gives horsemanship, is amazing. For 3 mana, you give a creature +2/+2 and you also make it unblockable, which is really nice for green. A lot of big creatures in green don't normally have evasion in order to balance them out (see: Terastodon, Witherscale Wurm, or Krosan Cloudscraper for examples of what I mean) and the main way in green to give evasion is with trample (which can be absorbed by blockers), having a way to make things unblockable in green is great. My only real problem with this card is that it's only at sorcery speed, which means you can't use the buff during combat. I guess that means you also can't block something like Cao Ren, Wei Commander with your Ghoultree, but how often does that come up? It is a little expensive too, but considering there are only 2 cards in mono-green that actually makes a creature unblockable (Tanglewalker and Trailblazer), it's well-priced.
Cons: Sorcery-speed, expensive when compared to non-green unblockable cards
*Note: I really hope that Wizards smartens up one day and prints Three Kingdoms in North America. It may piss off some collectors, but the flavour of the set is worth it alone. If they printed Kamigawa (Japanese set), why not print the Chinese set? The set might not have been the greatest, but people would snatch it up really quickly and Wizards would be able to add more to their mountain of money.