Icecold, what's the chance of decking out against a Half-Blood? Do you really need to counter that?
I personally wouldn't, but if you want to, you can still trim it down to 33. Half-Bloods have 64 cards and they draw 2, so 33 would prevent deckout.
Comments on the actual deck: I don't think the PUs are necessary. You have enough damage on the table as it is. Just remove 'em, also helps to speed the deck up. For 30 cards, after you remove them, take out an Aether Pillar and an Immortal. For a 33 card deck, add another Aether Pillar.
And that's it. Pretty good deck. Upgrade Lobotomizers next, then Dragons, then Pillars, then Immortals.