Unionruler's suggestion works well. Alternatively, if you adore your Immortals and don't want to remove them, I would remove 2 Phase Dragons and take 2 more Aether Pillars. But Union's version is better.
I disagree with what he said about mono
being restricted to AI3. Against Half-Bloods, mono
also dominates as one of the best monos to counter Lvl5.