Given that it's mostly fan fiction from the player base, I can appreciate most of these ideas. Median is all about making something work. Hell.. There's a churel paladin guide.
Maybe with sigma, some of these will convince slightly for new concepts? That's not my field to work with though. I just like the idea generation for potentially a more experimental and/or natural feel to each character class without having to go straight for an oskill.
I can only really heavily comment on necro since that's where I'm the most familiar. The venomancer is a cool concept. I've tried a malice necro a few times and was dissatisfied because the poison skills just seem too awkward. Funeral pyre can be used for heroics, but I think the cast delay (time between the cast and damage application) and the targeting mechanic make it tough to hit a moving target like Quov Tsin. I think it could be a more effective mechanic if it wasn't required to target an enemy, that way you could better aim it and/or predict the enemy movement so they walk through it. Besides that, the poison seems awkward, as I said. I think it should bring it a flare of the classic poison nova or some type of poison exploding missile. Maybe like the bloodstars that an amazon's bloodstorm shoots out and it has a small AoE explosion that could be increased with hard points (like every 6-10 points, add another yard or two.)
King8 said totem summons is the strongest build. I have to agree. Obviously, it depends on what your play style is, but in my experience, I have one-pointed all summons (apart from shadows for damage buff) and they've been plenty strong enough to tank and kill without much thought into it besides some minion stats boosts. I think black mass becomes less useful at that point, so maybe the Serpent Morph can go there. Potential skill would include poison pierce per hard point, spell damage, hissing sound effects.
The venomancer would give life to a summoner or totemancer so you're not just standing around letting things happen. Kind of more like a battlemage concept, maybe not as much as "lead your army" as much as support fire and applying poison damage over time to sync with your minions' damage.
Again. Before people get angry about this post, it seems strictly for player opinion. Not trying to make a class overpowered or bash on Marco's and the team's work with skill tree design.