Im not much for words so ill keep it short.
Volibear needs health. Stack it.
Max w first. You can use it to finish off squishy carries that are at mid to a quarter health.
I max q last because the chase speed does not scale.
Voli should initiate, and his teammates should follow.

Sometimes instead of Rylai's i will pick up Odyn's Veil if they have a fizz or other ap carry that im not faring well against.

What my build is missing is attack speed. I do sometimes miss opportunities to use my w because i haven't auto attacked enough to charge it. So, u might feel the need to add an AS item if u wish. It doesn't happen often enough for me to change it up.