Decent protection on every body part and a decent weapon. Protection is more important against the masses of spiders than being unencumbered: if they can’t bite through your clothes/armour, they can’t poison you. A leather jacket and leather pants aren’t a bad idea; I’d also recommend a helmet of decent coverage, some safety glasses, a protective mouthpiece or some other real mouth protection (a motorcycle helmet would probably work), layered protection on the hands, any decent pair of boots, etc. (And reinforce everything, of course.) That and a knife spear worked pretty well for me–I came out of a basement of like 70 spiders completely unscathed.
Alternately, a good bow with lots of ammo (there can be upwards of a hundred spiders in one of those basements) and a full flashlight. The spiders don’t hunt by sight, so the light’ll only help you, not them.
In any case you shouldn’t torch spider basements. There’s an increased chance of good loot down there–sometimes you still won’t get anything good, but RNGesus is a fickle god. That, and enough chitin to plate a bloody vehicle and enough meat to last you for years. (Or, if you don’t want to eat it, a nearby refugee camp might want some jerky or other preserved meat and not be too discriminating about what it came from. Or you could dehydrate it and make it into protein powder in an attempt to forget its origins. Or yada yada.) And, of course, plenty of experience for your weapon of choice and for Survival when you butcher them all.
