Veno is one of my favourite Heroes in Dota 2, as a support with a max of your Q you can kill pretty much anybody, provided your carry/offlaner actually wants to kill.
Now with 7.39d you max out plague wards, max plague wards early is very hard to clear since you can stack them up and it becomes an army versus anybody

Keep in mind that this build doesn't guarantee you will live through the fights in mid to late game, but with a good cast of your Ulti, your team can take care of the rest.

Remember: You are not a Late Game hero, so try to maximize your potential Early to Mid Game.