Cast E through or behind the target and walk while it travels so the return line is what roots for the pull; Swain top gets much more from that curved Nevermove than from throwing it straight like ordinary poke
Treat W like a footstep tax—on the retreat path after E, on your own body when they commit, or over a cannon they want—because Swain top gets real pressure when he takes away the next place the opponent wants to stand
Swain top looks best once fights get crowded and close enough that people cannot simply leave his range, while long isolated side lanes and a delayed early component are the patterns that make the pick lose shape
Side lane long enough to collect the wave, push it to a safe point, and disappear before the duel starts on their terms. If the enemy top or mid can run you down in open space, do not stay for the extra wave just because your ult is up. Your best pattern is usually catch, Q the wave while threatening E, then move toward the next place where people have to walk into you. Stay longer only when you know who answers, you have vision on the collapse, and the next objective is far enough away that you are not missing the fight Swain actually wants.
Swain's ravens collect Soul Fragments that heal him and permanently increase his maximum health.
Swain unleashes several bolts of eldritch power that pierce through enemies. Enemies hit take more damage for each bolt they are struck by.
Swain opens a demon eye that deals damage and slows enemies. Champions hit are revealed and also grant Swain a Soul Fragment.
Swain launches a wave of demonic power forward. It then returns to Swain and roots enemies it hits. Swain can then choose to pull all rooted champions closer. This ability has a shorter cooldown during Demonic Ascension.
Swain transforms into a demon and drains health from nearby enemy champions, minions, and neutral monsters. Swain can cast Demonflare to decimate and slow nearby enemies with a nova of soulfire. This form is indefinite as long as Swain drains enemy champions.