New to this game and idk how to beat adc's please help?
Okay; so i've recently came to league and picked a couple of champs that i enjoyed, 
,
and 
i seem to be doing quiet good on cs as i usually get ahead on them, i seem to do even fine in laning phase as i get out with 2 kills and get my first turret, the only thing i dont undrestand is how to beat adc's, my friend told me that i can get a bit of more armor on swain since hes kind of a mix between a mage and a tank so i got these items 
and 
but no matter how much i build armor the adc always ends up one shotting me i dont undestand is there something wrong? do i have to go resolve as secondary tree? i get it you need to catch adcs off guard, but i just had a game on which enemy kalista got a solo penta while we were all full health at baron, and vayne just tower diving us and had a 
and a 
we were full ap team and she tore us all apart while taking 0 damage, our ornn had 250+ armor and she bassicly 4 shotted him i really dont get it why does she mostly go full ad with a little bit of mr and take 0 damage? while our tank went full armor and died with like 5 hits?
as a secondary role and tf for me seems like my actual play style, i can land the Q when the enemy is about to last hit minions, i know when to use and when not to use certain cards and i can use ultimate to its best, (not saying im the best tf player) but the thing is, adcs seem to be unstoppable late game what do i even do to them when all it takes is one auto attack for you to die?
