My go to potions.
My oh ^$%$ poison: Lingering damage health & paralyze. Canis root, imp stoll, and one of the other lingering damage health ingredients.
Damage health & slow. For situations where I need some extra hitting power but I don't need the overkill. Deathbell and River betty.
Damage health & ravage health. I can't remember the ingredients, but what is not to like?
My favorite in Oblivion was still more fun.
Wraith Kiss: Damage health, damage magicka, frost damage, paralyze, silence.
Spoiler Really svcked in the fight where you had to fight yourself. Laying on the ground incapable of doing anything but dying really svcks. I knew how my enemies felt.
And killing hawks.... use lightning spells, instant hit makes it really easy.