Well this is my first Guide And my english was pretty bad so im gonna try to do my best

So ..They main Idea of this tanky style Swain was ... If they Focus u and cant get u then they die.Usually when i play Swain and i Harass Ppl they get quick into a ganking mode on me so i changed my Ap build to get into this cause if they gank me but im not alone then the other or my team with me gonna get em cause ppl just try to focus me but they cant get me so this is why i make this build this way

Im Making a tank swain but i dont want to get it useless so that's why i focus on AP Runes that's kinda my '' AP items'' cause u dont want to be just a tanky style u want to kill em and hurt em hard so ... that's why i use those runes

Usually i go mid but it could work on a lane but youll get less money for the build and it's gonna be longers to get but it would work too .
So when i got mid i just dont stop to harass with torment and when i can i give a nevermore to let him know that i am here btw torment and Ignite together usually get last hit cause they run and then they die this is really cool to use together to finish someone and u should always keep your ignite to finish someone unless this is just useless they gonna heal and youll need to wait forever that he get back so use it together always when he get low enough to use it so that's it ... And late game when they'll focus u use ravenous flock to heal yopurself anyway u should play a lot of game to learn the way to swain this is just my way and it work for me but maybe it wont for u .so Good luck trying !