Old
New
I think I prefer her new one.
It has a better color scheme of red+black, shows off her playstyle and figure, and leaves "mystery" in her character. You don't know what she's attacking, or where she is, it leaves focus on her with the contrast of her color against a brightness centering around her, but you know she's in danger despite her emotions not being clear whatsoever. The bats are a great touch, and reminds me of Van Helsing for some reason.
The old one was dirty. Red+brown+black+silver. Her bolt is glowing red for no reason, her ultimate crossbow looks fugly. She's holding her arm-bow in a strange way, and I'm still confused as to what she has behind her collar. Hair? Armor?
The new art direction is to feature a champion in their natural fighting mode, and I honestly think it's a good thing.