During the LCO, it was mentioned that zombie wards artificially inflate your vision score, so tonight, I ran a build using zombie wards, and sure enough? Each and every single game, I unlocked the progress for the event, completing Demacia.
I'm taking a break right now to watch BRO play in the LCK (my favorite teams in the LCK are Damwon, BRO, Arthur-HLE, T1, and DRX in about that order, with Yohan-HLE kicking the team down to like sixth or seventh because I am an Arthur fan and I think a lot of HLE's success is due to him and am not a fan of Yohan in comparison), but I may go back later tonight as well.
Turns out the build I'm running actually works pretty well, too. I'm running dark harvest + taste of blood (I know cheap shot is better for Ashe and damage, but I need the healing due to not building any sustain item) + zombie wards + ultimate hunter, with approach velocity + biscuits (the biscuits help me with mana, approach velocity helps me with mobility), starting tear and then building umbral glaive into manamune and then situationally Duskblade or Ravenous Hydra (although as support, vigilant wardstone gets built and I have the support item, too).
I'm not running into mana shortages and not really running out of HP and am dealing decent damage and huge vision, so. It's working!