Crystalline flask and 3 pots mid.
Lately I've noticed a lot of mids (AD/melee mids) go crystalline flash and three health potions. How do you deal with that? As a caster I don't have enough burst or mana early game to kill them and they just keep harassing me ( I harass back but they just outlast me till 6 then all in), and by the time I'm done with the one pot I have they still have 3 left.