What is the best way to counter full lethality as AP caster?

Build zhonyas hour glass, and dodge their abilties, by building lethality they become so much more ability reliant, dodge their stuff and they are useless.

Death is the best cc.

Id 10x rather play against an assassin with than against one with just tbh lol

There is not too much that you can do other than buy zhonya's and maybe tabis if its really bad. Other than that, most assassins are still fairly squishy and locking them down with cc will help you out a ton

play a mage with low cooldowns or multi hit spells, durable ones help

kill them

Death, the ultimate counter

More Armor than they can get through Most CDR from a single item Crap load of Mana

Burst them before they burst you.

Or build a shit ton of health. Idk.

Take either or . Build straight AP and burst them down faster than they can burst you.