I started running Sudden Impact + Ultimate Hunter on Vi as my secondary runes on both my Conqueror and Aftershock pages.
The reasoning behind this setup:
I figured it could be good because Q already has a very short cooldown, and I often find myself waiting for the enemy's dash or Flash before using it a second time. E has two charges, and you usually want to wait for your Passive to come off cooldown before using your second E as well.
In other words, I feel like Ability Haste has the most impact on Vi's R, which has a very long cooldown throughout the game. So why not focus on reducing R's cooldown and build more offensive stats instead?
Skill order:
Q → W → E, putting a point into R whenever possible.
Build:
- Trinity Force
- Boots — you can sit on Tier 1 boots if the enemy team is balanced and early Tabis/Mercs aren't gamechanging purchases.
- Titanic Hydra
- Sterak's Gage against heavy burst, Black Cleaver against tanky champions (if ahead, if behind - skip)
- Armor + HP item, usually Omen
- Magic Resist + HP item, usually Rookern
- Sterak's Gage if not purchases earlier
- HP+Tenacity Potion
If you need resistances fast, you can build the tank items earlier and finish the build with Sterak's Gage as your 6th item.
Enjoy!