Venomancer is an incredibly powerful hero, with an incredibly crippling downside. He can pressure lane with his passive and signature with virtually no cost. The problem? His stats are hardly better than a melee creep.
Veno has the lowest possible attack value of all heroes at 2, with his esteemed colleagues Crystal Maiden and Tidehunter. His health is the second lowest possible value at 6. He's only twice as strong as the wards he spawns...
Thankfully, he has a strong passive to shore it up a bit. Venomous Nature is FREE and spawns a Plague Ward EVERY TURN. It's very similar to Kanna, but without sapping strength from other lanes!
Obviously, this synergizes well with any card that improves wide board states. For example, Mists of Avernus and Venomancer can win the lane all on their own. Talk about an efficient kill.
While stranding him on a winning lane and forcing a response from your opponent is ideal, Venomous Nature still does work on contested lanes, especially if you can keep Veno safe. A free blocker that gets PIERCING damage in every turn will definitely help turn the tides.
Sadly, Veno's frail body and ramp up time make this passive nearly irrelevant on a lost lane - the floor of this passive is throwing away Veno and a Plague Ward to block 2 guys.
In case you're wondering, the timing of this trigger is on the deployment phase so it DOES NOT GENERATE one the turn he is deployed.
Compared to his passive, Sow Venom is really good in a losing or contested lane simply because they aren't necessarily paired with Veno himself (the hero himself being the downside, lol).
This furthers any synergies Venomancer with cards that benefit wide lanes (IE Mists of Avernus), as both his passive and signature create more dudes.
It's comparable to Dimensional Portal, in most cases this is a little worse than D.Portal simply because Plague Wards shoot before the action phase, so they do not shoot the turn they are summoned!
Building a deck around Veno is almost equivalent to building a deck around Kanna. He is less explosive but more powerful in a vacuum. Sadly, not all opponents have a vacuum in between their ears.
First of all, hero protection is a necessity for Veno - his stats are simply too poor!
Cards that buff creeps are also welcome, Mists of Avernus being the premier one.
Overall, I feel Veno serves a niche purpose. An efficient way to pressure lanes while being a secondary win condition that ideally shares support cards with your main win condition (Hello Kanna).