Horsemanship is a keyword ability.
A creature with horsemanship cannot be blocked except by other creatures with horsemanship. Creatures with horsemanship can block other creatures with or without horsemanship.
Aaron is attacking with a Lu Xun, Scholar General. Ned controls a Guan Yu, Sainted Warrior and a Canyon Minotaur. When Ned goes to block Lu Xun he may only block it with Guan Yu. The Canyon Minotaur cannot block it as it doesn't have horsemanship.
- 702.30a. Horsemanship is an evasion ability.
- 702.30b. A creature with horsemanship can't be blocked by creatures without horsemanship. A creature with horsemanship can block a creature with or without horsemanship.
- 702.30c. Multiple instances of horsemanship on the same creature are redundant.