We all know that Kassadin is excellent against Casters, each of his abilities practically spelling doom for most, but what if you chose to do blind pick and wound up against an AD heavy team with no real 'casters'? How would you go about trying to keep yourself alive while still taking the kills or generally be useful to the team?

I like to use Kassadin a lot, and I was wondering how you guys might use Kassadin against someone like Master Yi or Lee Sin?

Just focus the squishier AD's, build some armor, etc. Playing kass against an AD heavy team is called getting counterpicked, just gotta deal with it

Kassadin, imo, is extremely underpowered in the current meta if played against a competent team. Although he is a somewhat potent anti caster, he has no wave clear, is melee, can be easily bullied out of lane pre-6 if your lane opponent has some sense on what youre doing. Also, kassadin would only really be viable as a last pick, as he can simply be counterpicked by an ad champion like talon or pantheon and be destroyed in lane, which kassadin really has no answer for with his 17 base armor.
Btw, blind pick has made blind pick unplayable.