The Chain Veil
Do the Superfriends say that? I don't know - DC sucks. Sorry, it's true. Marvel for life.
This is a good card in the right deck. This is confusing flavor-wise but If you have enough Planeswalkers to take advantage of this. If you do, it's likely you have 100 cards in your library. Standard decks might run quite a few planeswalkers but I don't know if they want this card, especially since it's a bit of a liability in a format with Hero's Downfall threatening to keep you off of walkers.
All in all, this didn't need to be mythic, but in the right deck this can give you a humongous advantage. It needs to hit quite a few walkers to be better on average than a card like Rings of Brighthearth so prepare to load up on walkers. This is going to be a real dud in sealed pools. I don't see much financial relevance here outside of foils.
Also, first Riki Hayashi tweeted that this does not go "infinite" with untap effects, and then today he said it did. Check Twitter for a final ruling. If this and Ral Zarek become the best of super friends, expect a little more play, but probably not enough to go nuts over.
Kurkesh, Onakke Ancient
They waited and spoiled this guy last and I am glad they finally spoiled him. This card is great in EDH. Decks built around Slobad, Goblin Tinkerer or Godo, Bandit Warlord or Bosh, Iron Golem could all use this guy, but he's also a sick build-around. I like this entire cycle and I think this is going to be financially-relevant in foil. Also, of all the cards in the cycle, I think he's the most likely to be undervalued initially. He looks like a bulk rare to people. Scoop accordingly.
Act on Impulse
Draw 3 cards. Exile them at the end of the turn. Except with upside. Nutty.
This is a low-on-curve hero that a sliver deck needs. I don't know how inclined we are to try 5 color slivers with no Cavern of Souls in the format, but we'll see how it goes. I like the fact that we have a few months of sliver nuttiness in Standard.