Perdido Street Station: Isaac kills the slake-moths by hooking his crisis engine up to the alien minds of both the purely logical Construct Council and the utterly chaotic Weaver to create an irresistible feast on which the moths gorge themselves until their stomachs burst. While manipulating the profoundly sociopathic Construct Council and its cult into rigging it all up in the hope of taking over his crisis engine and becoming a god (a problem dealt with by a simple "elyctric valve" and the precaution of performing the showdown miles away from the council). Note that the whole thing happens during a shoot-out with the Militia.
Perdido Street Station: Yagharek wrapping his whip round the neck of the final slake-moth and throttling it in order to free Lin. Bear in mind that because the slake-moths wings can instantly hypnotise anyone who looks at them, Yagharek does all this whilst facing away from the slake-moth.
Iron Council: TIME GOLEM. 'Nuff said.
Can we just give honorable mention to the small army of Gunpowder Golems Judah used to repel the militia chasing the group in the desert?