Senna vs Karma

Attack the souls held by the Mist whenever you can: each soul freed with Absolution (passive) increases your AD, attack range and crit chance.

Fire Piercing Darkness (Q) through an ally or an enemy to hit both: the beam heals your allies, and damages and slows enemies in the line.

Cast Last Embrace (W) on a target that's already slowed or immobilized: after a short delay, they and nearby enemies are rooted.

Cast Curse of the Black Mist (E) to engage or escape with your team: allies who enter it are camouflaged, then fast and unselectable.

Cast Dawning Shadow (R) to save an ally across the map: the beam has unlimited range and shields allies.

Play carefully at the very start of lane: Mantra (R) is available from level 1, so Karma already has an empowered spell.

Move away as soon as Focused Resolve (W) tethers you: if the tether holds to the end, you take damage again and get rooted.

Quickly leave the ring of fire left by Inner Flame (Q) empowered by Mantra (R): it slows and deals extra damage.

If you can reach her, focus her in teamfights: Mantra (R) then Inspire (E) gives a shield and move speed to every ally grouped around her target.