Senna's Piercing Darkness (Q) damages enemies while simultaneously healing allies and has long range, letting her overpower Soraka's heal-based war of attrition with poke while safely harvesting souls.

Braum is a melee champion with no ranged poke, so Senna can kite with long-range Piercing Darkness (Q) and farm souls freely with nothing Braum can do to punish her.

Yuumi is extremely vulnerable when not attached via You and Me! (W), fully exposed to Senna's long-range Piercing Darkness (Q), and gives no lane pressure, so Senna stacks souls freely and scales.

Sona has very short range and a fragile body, getting chipped down one-sidedly by Senna's Piercing Darkness (Q) poke, and Last Embrace (W)'s root lets Senna force an engage before Sona's Crescendo (R).

Zenith Blade (E) is a linear skillshot that can be dodged, but on hit it roots Senna and moves Leona to her. The follow-up Shield of Daybreak (Q) stun and Solar Flare (R) leave immobile Senna little room to escape.

Nautilus dives with a chain of CC from Dredge Line (Q) hook into Staggering Blow (P) auto-attack root, and the squishy Senna has no dash to escape.

A single Rocket Grab (Q) from Blitzcrank pulls in the mobility-less Senna and instantly kills her, punishing any positioning mistake.

Pyke's Bone Skewer (Q) hook and Death From Below (R) execute easily finish off the low-base-health Senna.

Rell's Ferromancy: Crash Down (W) frontal engage and point-blank CC pin down the escape-less Senna, and her tankiness means Senna can't burst her back.