The singular iron spider is destroyed from the gigantic army of tyranids, yet after this a canister is fired and lands on the invasion force, immediately destroying anything it hits, causing the spore minted to explode etc and then releasing a massive cloud of black smoke that blinds and suffocates anything within it instantly. Huge swarms of flying machines then circle around the hive ships and blast them to pieces with their heatrays before dropping explosive canisters all over the battlefield to deal with any remaining tyranids.
