Dude 4

Hunter/Huntress character because I know you Flak and you will make nothing but badass melee DPS and I will probably make nothing but bitchin' casters so I thought of a badass ranged carry.

The core idea is that she's a devoted huntress character, so single target DPS and skills that let her focus one target. Think like Poppy meets Vayne, but not nearly as frustrating or horrifically overpowered.

Core mechanic is a mark, lasts a relatively long time (possibly actually until it's removed/changed) with a cooldown equal to its duration (or if infinite, a decently long one), doesn't do anything in itself, but she has other abilities that do bonuses based on who's marked. Can turn it off at any time, but it won't be available for the remaining duration (easiest way is to make it two abilities, one that marks and one no CD that removes the mark, with the mark going on cooldown straight after it's used)

Second skill is a trap, a la Nidalee/Caitlyn. If it hits a marked enemy, it snares them and damages, if it hits a non marked enemy, it slows them instead. (not too keen on this idea)

Third skill is a passive, she gains health when attacking marked enemies, but loses health when attacking non marked enemies if someone is marked (so if she removes her mark she doesn't gain or lose health from attacking)

Fourth skill is another passive, basically the same as the third skill but with movespeed. Will gain a slight speed boost every time she hits a marked enemy and is slowed a small amount if she hits a non marked enemy when someone's marked

Ultimate: Poppy's but not stupid. Basically, she loses all allied vision but her own and that of her marked target, regardless of where her mark is. She gains movement speed when travelling towards the mark, and does greatly increased damage. Maybe becomes immune to CC? I want to say no to that.