A grisly fate awaits
Parasitism of spiders by wasps is very common, usually indicated by a small grub hatched from a egg laid on the abdomen of the spider. The grub feeds on the spider but usually doesn't affect it much, until just before the final moult, which the parasite can sense coming presumably through hormonal changes, when it sucks the spider dry overnight, then drops off to pupate somewhere. And you thought you'd had a bad day. Wasp's gotta make a living.
Metellina spp. Wasp? Who knows?
Canon MP-E 65mm F2.8 G SSM
f9 1/160 ISO 100