Guan Yu, Sainted Warrior
Legendary Creature — Human Soldier Warrior
Horsemanship (This creature can't be blocked except by creatures with horsemanship.)
When Guan Yu is put into your graveyard from the battlefield, you may shuffle Guan Yu into your library.
Qiao Dafu
Rulings
If Guan Yu, Sainted Warrior is removed from the graveyard after the ability triggers but before it resolves, it won't get shuffled into your library.
(wotc • 2009-10-01)
Despite the similarities between horsemanship and flying, horsemanship doesn't interact with flying or reach.
(wotc • 2009-10-01)
If a replacement effect has Guan Yu move to a different zone instead of being put into the graveyard, the ability won't trigger at all.
(wotc • 2009-10-01)
Rulings
If Guan Yu, Sainted Warrior is removed from the graveyard after the ability triggers but before it resolves, it won't get shuffled into your library.
(wotc • 2009-10-01)
Despite the similarities between horsemanship and flying, horsemanship doesn't interact with flying or reach.
(wotc • 2009-10-01)
If a replacement effect has Guan Yu move to a different zone instead of being put into the graveyard, the ability won't trigger at all.
(wotc • 2009-10-01)