Not Updated For Current Season
The masteries shown here are not yet updated for the current season, the guide author needs to set up the new masteries. As such, they will be different than the masteries you see in-game.
OK, this is my first attempt for a build. So sorry if it's looks a little bit messy, and i would like to apologies for my bad english...
So Swain. This character is a pretty good mid, but he is viable in line. You can play him solo or with someone, it doesn't really matter. But I suggest you to take mid. With your Ultimate, you will be able to stay in line for a very long time.
As Summoners spell you can take Clarity/Gosth. Flash/Ignite, Clarity/Ignite. I often go Clarity Gosth for reason you'll read further on.
Early game :
You have to rush your Rod Of Ages for the simple reason that you need a little bit more life to hold your line. PLay more defensive than aggresive. You need to farm to be very effective and you are the mid, so be patient, wait for your ennemy to make a stupid move and get caugh into your nevermove.
Mid game : You should have your Rod of Ages and your boots of mobility. Some people may ask why boots of mobility? It's simple. If you take those boots, you will have more speed than your ennemy ( except for Rammus, master yi ) so you will be able to chase them down and do your Nevermove. IT gives you a little advantage over your ennemy. Never forget that your Ultimate take mana Over time, so try not to be a mana hunger and save it for when you are sure you can kill your ennemy.
If you see you are doing good, get a Mejai's. You will have more ability power. But if you do, don't be surprised if the ennemy start focusing on your swain.
Late game : Swain have plenty of life, but he is NOT a tank. Stay behind your minions and try to help your allies. Go into their line, help them a little bit then get back into your line. You can take the Golem Buff everytime you can. It will helps you staying in the line longer and do your Ultimate for a longer time.
Random Swain Tips :
Swain can restor is life with his ultimate... Even with that... YOU ARE NOT A TANK!
Try to do your nevermove where the ennemy will go, not where they are.
Try to do Torment before any others ability. It will help you do more damage.
Swain is better Ap, don't go Ad.. NEVER!
And for God sake... DO NOT JUNGLE WITH SWAIN!
I will add more information later, but I think it's a good start.
Suggestion? Comments? Really appreciated!