Gwen vs Nasus

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.

Early on, take a trade whenever he steps up to last-hit a minion: each kill with Siphoning Strike (Q) increases its damage for the whole game.

Freeze the wave near your tower: to farm with Siphoning Strike (Q), he then has to step up and expose himself to ganks.

Once he hits level 6, don't engage during Fury of the Sands (R): for 15 seconds, he gains health and resistances, and his area damage scales with your max health.

In teamfights, if you're ranged, hit him while backing off: he has no dash, only Wither (W), a slow that grows stronger over time.