To be perfectly honest? I think that Fateweaver is too expensive for such a small army and leaves too much of a combat burden on the 2 Princes. Yes, Lord of Unreality and the Staff of Tomorrow are very nice, as is the sheer number of powers available, but I cannot help but think that spending, say, 280 points on a Lord of Change (ML 2 with, say, 2 Greater, 1 Lesser, for survivability and the explodey staff. Or 1 exalted (portalglyph) and 1 greater) would do you better. Those things have a nasty combat stat-line, unlike "Mr. 1A at WS2."
I'd also advise using the other 20 points to buy the Grimoire Prince a Greater Reward.
What sphinx of plascrete and adamantium bashed open their skulls and ate up their brains and imagination? Imperator! Imperator!