The various Oath enchantments are clearly
inviting people to build a deck with lots of
planeswalkers (bonus points, I assume, for using
the actual planeswalkers depicted in the Oath
enchantments). And aside from the question of
why there weren't cards in the enchantment block
Theros with similar designs that count
enchantments, there is reason to think that such
a deck might be fun, even if it's not top table
material for Standard tournaments. I expect Oath
of Jace to be a big part of what will tie any
such deck together, with both its
comes-into-play ability and its ongoing benefit
helping you find more planeswalkers to take
advantage of the bonuses from the Oaths of
Gideon and Chandra. Even a deck that's not
explicitly designed along those lines might want
to consider it: the card drawing is perfectly
fine by itself, and enough decks use
planeswalkers like Liliana of the Veil and the
various versions of Elspeth as part of their
default game plan that they can scry 1 most
turns, which adds up over time.
...sigh. Damn it, they're trying to make
standard superfriends a thing again. As it
stands, This oath, is of course, the best oath,
providing both scry opportunities (scryportunities?)
as well as the whole draw thing. legendary
status hurts it a bit, though i suppose scrying
your arse off would make for super slow and
broken games.