Gwen vs Swain

Land 4 autos before Snip Snip! (Q): each auto adds a snip, on top of the first and the last.

Land the center of Snip Snip! (Q): in the center, part of the damage becomes true damage and each snip applies A Thousand Cuts (passive).

Place Hallowed Mist (W) against poke and ranged CC: enemies outside the mist can't target you, except towers.

Cast all three Needlework (R) activations within 6 seconds: the first throws one needle, then three, then five, with growing damage.

Get out of the Nevermove (E) path as it comes back: it only roots on its return to Swain, then he can pull each rooted champion to him.

Leave the area as soon as Vision of Empire (W) appears: it strikes and slows 1.5 seconds later, and each champion hit gives him a Soul Fragment.

During Demonic Ascension (R), back off and hit from range if you can: he only drains nearby enemies, and his form ends when he stops draining.

If you have Grievous Wounds, apply it during Demonic Ascension (R): the drain heals him every second, and that healing keeps him alive.