~We have some solid confirmation of the abilities but no spoiled or previewed card yet.
We also do have the card art for this white Planeswalker so here is the marriage of the two in a fairly terrible image made with MS Paint (so don't yell at me please).
Here is my mock-up of the Bant Planeswalker, 'Elspeth, Knight-Errant'
Planeswalker - Elspeth / Mythic Rare
+1: Put one 1/1 white Soldier token into play.
+1: Target creature gets +3/+3 and gains flying until end of turn.
-8: For the rest of the game, all your enchantments, artifacts, creatures, and land are indestructible.
Some other cards that we are following right now in rumor-mill . . .
Knight of Eos 4w
Creature - Human Knight "Uncommon? Rare?"
When Knight of Eos comes into play, put two 1/1 white Soldier tokens into play.
1, Sacrifice a Soldier: Prevent all combat damage that would be dealt this turn.
Ad Nauseum 3bb
Reveal the top card of your library and put that card into your hand. You lose life equal to its converted mana cost. You may repeat this process any number of times.
Knight of the White Orchid ww
Creature - Human Knight "Uncommon?"
When Knight of the White Orchid comes into play, if an opponent controls more lands than you, search you library for a plains card and put it into play tapped. Then shuffle your library.