Poison has a base damage of 35 each application.
20 minions applying poison each second = 35 damage each poison X 20, giving 700 damage.
This is increased by 200% because each stack increases poison damage by 10%, so now we have 2100 damage after 1 second.

second 2 applys another 700 damage, and another 20 stacks, giving us 1400 increased by 400% = 7K dps

Your post reminded me that I wanted to build a pure poison druid
With poisoning thorn totems, poisoning thorns, a poisoning scorpion and poisoning grasping vines creating additional vines through spriggan and passives, it SHOULD work fine.
Early game I can say that poison is very weak, with ticks of 9-15 depending on stack numbers, because the base damage of a poison stack is the TOTAL damage over 4 seconds, not per second.
So, with 20 minions (which is hard to achieve that all those minions actually provide one stack per second, but let’s go with this…also since minions can stack multiple stacks per attack if their Chance is >100%) that would calculate as:
~7 damage per second x20 = 140, x300% = 420 damage first second
140 + 140 = 280 x500% = 1.400 damage second second
280 + 140 = 420 x700% = 2.940 damage third second
420 + 140 = 560 x900% = 5.040 damage fourth second
after that the first round runs out so the ceiling is 5.040 dps. Without any buffs to poison damage.
So it’s much more in line I think, and other chars can probably achieve similar DPS numbers in the endgame.
But I really like the Basic premise of poison damage, since you don’t Need any offensive stats apart from DoT%, Poison Chance% and Poison Damage%. No crit, no spell damage, no minion damage (I think?). Maybe cast-speed? And apart from that everything can go into defensive stats. Same with nodes, where you’ll only Need very very few offensive ones.

Are you sure about this number? I never put that much thought into damage over time builds but isn’t there a stat that increases the dot dmg and without investing in it it’s more like a stroke of a feather every now and then? Or is this something completely different for pets?

This explains why poison has been so unsatisfying to play. Scaling 200 or 400% of 9 damage is useless. Since I’ve been trying to use minions to apply the poison, you have to keep them alive, yourself alive, then put points into chance to poison, then points into more or increased damage, then find ways to increase attack or cast speed so the ramp up time isn’t glacial.

Or is this something completely different for pets?

I believe minion damage and minion damage over time will scale minion’s poison damage, but scaling rubbish still gives you rubbish, and Elgereth’s numbers seem even too high: the clearspeed for the minion poison builds I’ve started is abysmal.

Yeah, this is the Basic theory, I don’t have the time to thoroughly test such Things (or better said: I don’t want to spend my bits of free time testing this stuff ), and this calculation is of Course the BASIC DPS without any +%-damage. With +DoT damage, +poison damage, +poison Duration this can of Course increase quite a bit, and I don’t have DPS numbers to compare them to.
I also wondered if +Minion Damage actually increases their Poison damage, as +Spell Damage for you doesn’t increase your DoT damage, and I’m not sure if +% Damage on you even affects poisons base damage.

But yeah, so far (5 poison totems and poison thorns on myself) it doesn’t produce useful numbers, even fully poison skilled the actual physical damage of the thorn totems per hit is much higher than the poison ticks.
Maybe the calculation is off somewhere? For example, that only new stacks gain the appropriate +10% damage increase?
(Basically: First stack does 10 per tick, second stack 11 (because 10+10%), but the first stack remains at 10 instead of being increased to 11 as well?)

The Special Thing about poison is, that each stack is supposed to increase the total poison damage on the mob by 10%. So when you can stack massive amounts of poison stacks onto enemies, the damage SHOULD increase dramatically. And when you have 7, 8, 10 minions that all poison you can generate way more hits than you could alone, that’s why minion poison seems the logical way to go.

Well its +10% increase poison damage per stack. This means it added on with your other increased poison damage boosts.
Since any poisoner will have increased poison damage the apparent effectiveness of stacking it will be reduced.
If you have +100% increased poison damage (or 100% minion damage) you be doing 200% poison damage base. Add 10% increased damage from poison stacking and you increased poison damage to 210% for a 5% increase in numbers from what you did before.

It only its more poison damage or more damage (global) that will multiply with it.

Patch 0.7.3 - After further testing, I’ve found a minion poison build that possibly works: Acolyte lich/necro.
The key thing that appeared to be missing is that aura of decay is essential for any poison attempt, especially a minion one. It is particularly OP unbalanced at the moment, which makes up for the really UP unbalanced minion poison nodes. The 150% buff to minion poison damage and 100% chance for minions to poison is amazing. These 5 points in aura of decay are seemingly 3 times more effective than the 80 points I put into the 4 other skills…

Skills - spectral spirits - take whatever mix of the poison nodes and cooldown nodes.
skeletal mage - either casters with lots of extra projectiles + poison chance, or deathknights with cooldown reduction.
skeleton rogues - they suck a bit so will try archers or warriors casting bone armour
wraiths - poison chance and cast all at once nodes.
Passives: Just take all the int, life, life regen and vitality you can.

Levelling: you just have to plug away until you get aura of decay. As this thread suggests, minions with poison is extremely painful, and without aura of decay you’ll struggle through even a level 1 monolith.