Curator's Ward

Oracle Text
Enchant permanent
Enchanted permanent has hexproof.
When enchanted permanent leaves the battlefield, if it was historic, draw two cards. (Artifacts, legendaries, and Sagas are historic.)
Card Rulings
4/27/2018 If Curator’s Ward is attached to a historic permanent you don’t control, you draw two cards when that permanent leaves the battlefield, not that permanent’s controller.
4/27/2018 If you give hexproof to an opponent’s permanent, such as by enchanting it with Curator’s Ward, that player can still target that permanent, but you can’t.
4/27/2018 A card, spell, or permanent is historic if it has the legendary supertype, the artifact card type, or the Saga subtype. Having two of those qualities doesn’t make an object more historic than another or provide an additional bonus—an object either is historic or it isn’t.
It can give a fragile commander (or any fragile combo piece) some protection, doesn't lead to card disadvantage if the card is killed anyway, and gives card advantage if you bounce or flicker your own protected permanent.
Great versatility.