The two biggest problems with Swain.
I'm not talking numbers, I'm talking fundamentals.
First: This is the lesser. His ultimate is both DPS and burst. A long sustain damage followed by a massive burst of damage.
Second: This is worse. His Q is blocked by minions. He E roots on the furthest back enemies. Do you see the problem? For one ability you must stand behind minions and for the other in front. This makes it so wherever you stand he can harass you.