I used to play Swain like an AP carry then after I got **** on enough I decided to take another route. This is what I have come up with. I'm not writing a lot so this is just a quick guide. I may end up making it longer but for now this is it.

I use these runes because Swain needs the Magic Pen more that more flat AP. I don use the mana regen because I like him to be tankier early game and if you dont have blue all game something is either wrong with you or your team so it doesnt matter. Swain without blue is awful, for you and everyone else, except maybe the other team.

These masteries are self explanatory. I liek to be tanky with more CDR and the 10% magic pen. I have switched the 9 in attack to support in order to get the longer blue buff but I found that I was less successful with that route so I pretty much stick to this. You may be wondering why I chose to put 2 points in Butcher and 1 in Brute Force, that is because Swain has a tough time farming in the early to mid phase of the game, especially if you are getting pushed alot. So I use the masteries to give that extra AD for last hitting. Last hitting is always important

I like to start out with the health regen plus a helth pot. I have been successful using boots and 3 health pots but I don't like not having the sustainability that the health regen gives you. I also switch between mana and helth pots to start off depending on which champion i am facing. If I am facing somebody that I can initiate on like Kat or other weird mids like her I use mana pots becuase I use my abilities alot.

The skill sequence is simple, always get your cc first because you should be using it to guard your jungler, then get your damage spell and then get your slow to help land those snares. Max out damage first and then slow and then snare.