Counterspell is good, but you probably could put a Mana Drain in that spot. Instead of Void Shatter, play Perplex. This card literally says "foolish mortal, I'm going to hurt your brain." It's also a great way to tutor up a lot of tasty 3-drop spells in this list, like Deliver Unto Evil, or Counterflux (if you know someone has a Flusterstorm in their deck.)

Thanks for the comment!

Unfortunately I only own one copy of Mana Drain, and I have it in my Jhoira deck. If I had another though, I'd certainly throw it in here.

Perplex is an interesting option. Any idea what I could cut for it?

You need to think about the MTG character your deck is trying to sing to here. Void Shatter sings to Jace. Perplex sings to Bolas. The deck sings Bolas more than it does to Jace. Cut VS for Perplex.

Just thought of something, you've got the wrong Decree card. Decree of Pain is better. It's cheaper than Annihilation and doesn't exile or hit lands. I understand the need to wipe away lands as part of a game-finisher, but don't run more than one. Obliterate is fine since it only destroys, plus you could still get lands back if you were to run something really filthy like Crucible of Worlds.

If you can some how fit Nicol Bolas in there for that last bit of flavor and functionality, that would make this deck awesome. Id' personally cut Ob Nixilis, Unshackled for it, since it doesn't really reliably hurt everyone (unless you have another card that forces everyone to routinely tutor for things), but that's just me. You could probably get Nicky B. from cardkingdom.com if your local game store doesn't have one in stock.

There was a time where Nicol Bolas was the commander, however he's just too clunky to really make work. Sure, if he hits it's devastating but the combination of his high CMC, upkeep cost, and the fact it doesn't do anything until at least the turn after he lands.

Also, as far as decrees go, Decree of Annihilation is a major win-con in the deck. It doesn't get rid of Planeswalkers or enchantments. So as long as I have enough Planeswalkers out, it literally hands me the game: With no board and no mana to cast spells, most people either scoop or sit around for a few turns until I can get some ults off and win. I don't think I've lost a single game where I resolved it.

I once had a Crucible of Worlds in here, and I can look into getting another one. It certainly is a strong card.

If you're running Bolas, the Deceiver, I think you should consider Visage of Bolas as a mana rock. It's inefficiencies as a rock (4cmc) get a bit balanced out by being able to tutor out a planeswalker. But I can understand not putting it in, I'm thinking of cutting both from my own deck. Still, since it's not a widely available card (came out in the same planeswalker deck as the Deceiver), I figure a lot of people just don't know about it. It's one of the very few passable planeswalker/rare tutor combos that I've ever seen come out of a planeswalker deck. It just seems like if you can fit one of them, it's hard to think the other can't fit.