Frode paused in his graffiti-ing of Nurgle's Garden, in the middle of carving the chemical formula for bleach through the Plaguefather's armies.
He made a slightly rueful sound. While the shields were holding for the moment, the City-Titans represented too much of an investment in time and resources to simply remake them after they'd been consumed, at least mid-battle. So a fragment of his concentration went to work.
First, the titans shrank visibly, by a couple of hundred metres. Then they abruptly sprouted so many (relatively) slim spines that they looked like oddly-proportioned sea urchins. As a followup, in case the worms could handle being suddenly turned into colanders, the spines grew a spiral monomolecular blade down their length, and began to spin at incredible speeds. Anything punctured by those spines would be drawn downwards by the drilling motion, into the storm of blades at the base where the spines met, and be reduced to a fine mist. As a final precaution, the spines electrified violently, bolts of lightning earthing themselves all around.
All that accomplished, the titans went back to trying to restrain the mansion, ramming against it with areas that lost their spines on contact, so that the mansion wouldn't get accidentally caved in on Edward and Isha, and Frode resumed vandalizing Nurgle's garden with the DNA diagram for penicillin.