Short and sweet, I made this build because I was annoyed by shooting my r at people and having them live. Vel is my main, and I thought hey wouldn't it be nice if I had runes that doubled my poke? That's this. Low CD's mean you do not need to be afraid to spam your abilities, including R. After you get some stacks, it basically is your passive x2 which is fantastic. This rune page and item list are for straight melting people: simply delicious.

My engage is typically a Q to slow the target, followed by a W rift. The 2nd W burst will activate the passive. If you hit E, throw a W to get a good passive poke on them. If they are not super mobile, Q, W, then R will usually do. If they do not melt and charge you, E then run while spamming Q behind you.
Legit just spam everything all the time, especially W in lane since you have low CDs. If you can get a DH stack, shoot your r at em.