Regarding Wagamama's Void build, he is right, it is enough to survive Invoker's combo, which is a huge nuke from which you can instantly regen by time walking. All Void needs is to survive the nuke. It makes sense to go Vanguard / Skadi.
i do not agree with skipping necro 3 on arc warden, you're throwing away a lot of your kill, push, and deward potential by skipping it
Push and deward, I agree with.
I would even say throwing away a lot of farm: by just sending the necros in the jungle camps all over the map, you can farm pretty well (something like two camps per activation of necros). All while randomly dewarding.
Kill potential? This is a very little potential: noobs get killed by being low health and killing greedily the necros, yet in the VHS bracket, people either farm the necros, or flee, and there is no way to get the kill, even with a diffusal and a blink dagger, the most common heroes (Ember, WR, Ursa, Lifestealer, etc.) will flee with very low health but still alive. You would need an Abyssal, or maybe an Atos to keep them in-place. Or a buff to Necros' movement speed somehow.