That depends significantly on which 5 challenges you're running.
Later boss potions: Dm-300: purity can be useful for his poison gas, haste or invis for the chase sequences
Dwarf king: anything that does aoe. Poison gas, liquid flame, and many exotic potion variants that create large damage zones
For yog I use a very specific alchemy load out, as follows.
1x arcane armor (exotic paralytic potion plus goo) Reduces damage from most of the fists plus any yog lasers you don't manage to dodge
1x toxic essence (exotic poison potion upgraded again) poison immunity makes the stinkfist easier
2x dragonblood (exotic fire potion upgraded again) fire immunity makes the fire fist a lot easier, and burning grass+immunity to that blaze makes the grass fist much easier
2+ magic sight potion. Makes the light and dark fists easy