[Vicious Love]

Well, your hunter spiders, hoplites, mechanical men and undead would be completely and utterly useless, and only marginally useful if enhanced by Weapons of Sharpness. A pretender's MR can be pretty damn difficult to penetrate, so Disintegrate is out of the question. And you haven't got any astral mages to Magic Duel the target.

Mid-level magic items, eh? If that means Smashers, Duskdaggers, Hammers of the Mountains(or whichever hammer is armor-negating) and maybe, maybe Ethereal Crossbows, you might actually stand a chance, provided you've got survivable, high-MR commanders who can bear said arms, and the Sphinx isn't in high friendly dominion. I don't suppose you've got a high-strength astral mage around who can wield two Swords of Swiftness, or a Smasher in each hand? Nothing quite like 2-4 uber-high damage armor-negating attacks per round to bring an immobile colossus down.