When the permanent enchanted with Curator’s Ward leaves the battlefield, if it was historic, you draw two cards. If it's anything legendary, or an artifact, or a Saga, it's historic. Popping this on a Saga is cute since a Saga leaves the battlefield after it's run its course after three turns. But you can use it on whatever you’d like that needs protecting from removal.
Curator’s Ward has actually seen play in the sideboard of a Sword of the Meek combo deck in Modern. There's a lot of Commanders who would love to be equipped with this, too. It's definitely a card to pick out of bulk boxes and it's a useful addition to anyone’s collection.