Just throwing out some ideas for what she could be like as a hero:
Q: Roudhouse Kick: Deals physical damage in a short area in front of Marci, similar to Gods Rebuke, knocking the target in the direction they are kicked. Vector Targeted.
W: Shoulder Check: Marci runs with additional speed and shoulder checks the target, knocks back and if the target hits another enemy unit, it stuns both. Like a Shackeshot, but cooler.
E: Spotter Call: Marci whistles to give the closest ally True Strike and bonus damage on their next attack.
R: Finisher: Requires a wall, structure or tree in range. Slams the target's head against it, deals physical damage and slows, Cooldown is reduced if the target is killed.
Some alternates I though of:
Disarming Hold: Active skill that disarms the target and reduces their speed to zero, you deal additional damage if you attack them for the duration.
Brute Strenght: passive ability that makes Marci's auto-attack make additional attacks on a cooldown. Think Swashbuckle with less range and mobility/utility. Basically a DnD Monk.
Spotter (Ult alternate): Marci channels and gives allies a true strike aura for a limited duration as she calls out their shots.