Paralysis no question then get your hits in, damage health never equates to the hits you can deliver.
Man, those Two Handers can very scary for warriors too.
Lingering Damage Health does 5x as much damage as Damage Health, but it takes 10 seconds instead of being instant. For example, at 50 Alchemy, no perks:
Imp Stool + Mora Tapinella: 5 damage per second for 10 seconds (50 total)
Imp Stool + Nightshade: 10 damage
For the second potion, Deathbell instead of Nightshade makes it 15, and River Betty makes it 25, so that closes the gap a bit. Obviously, adding Canis Root makes them both paralyze.
I don't think it's possible to make a Lingering Damage Health + Slow poison, though.
That's a waste...Crimson Nirnroot + any other Damage Health ingredient does more damage than Crimson Nirnroot + River Betty. It looks like a bug where River Betty is overwriting Crimson Nirnroot, even though it shouldn't. Try it.
Weakness to Fire + Fire enchanted weapon.
Oh, sorry.
Anything with paralysis, as this gives you time to either back away or finish the job.
Stacking poisons is okay, but they're also tediously slow, especially at high levels.