my main is adc vayne, but because of call order, i need to find a new champion to play if adc is taken. i need a champion who can use pretty much the same rune slots like wu kong, but even if i could use wu kong i still need a good midlaner if adc AND support are taken. Do you peeps have any suggestions?? ^v^
yasuo?
what about 
or 
For AD mid laners, you could look at Yasuo, Zed, Talon or Varus.
I'd suggest avoiding champions like Yasou or Talon, just since they tend to be low impact, unless they get incredibly fed early. Other AD mids, albiet slightly off meta picks could be:
Pantheon Wu-Kong J4
Realistically, you can do relatively well with almost any brusier.
Azir.
TF would probably actually be okay to play mid with AD runes, even if you do go an AP build in game. Or just play AD TF?
Zed is the only mid lane caster I can think of (shrug), unless you'd like a mage then I'd suggest leblanc.
Vayne mid is actually pretty strong. You could try out mages that play similar to ADCs, Cassepoia and Ryze both do pretty heavy sustain damage from a similar range to an ADC but provide a different damage type, obv they need their own rune set.
If you have to go AD runes then I would play an ADC mid like Ezreal, Vayne, or maybe MF if your team needs AOE and just roll with that. Other good options are AOE teamfight champs like Lissandra, Orianna, and Viktor.
