Creature — Wall 4/4, 3W (4)
Rare
Defender (This creature can't attack.)
Flying
When Ageless Sentinels blocks, it becomes a Bird Giant, and it loses defender. (It's no longer a Wall. This effect lasts indefinitely.)
Illus. Tony Szczudlo

10/4/2004: It becomes both creature type Giant and creature type Bird.
8/1/2005: Once it stops being a Wall, it can attack because it also loses Defender.
Legal in Vintage (Type 1)
Legal in Legacy (Type 1.5)
Legal in Classic (MTGO)
Legal in Commander