It is worth remembering that once unlocked the recipe will be automatically available in all saves, so I recommend experimenting on a new game on a low difficulty level.
Higher quality potions are achieved by adding better quality ingredients. However, to raise the level, not all ingredients need to be of the same rarity. Each additional level of rarity adds to the level of effectiveness (the Roman numerals next to the potion name). Uncommon (green) adds +1 effectiveness, Rare (blue) adds +2 effectiveness, and Legendary (purple) adds +3 effectiveness.

The effects listed here are the values for using common (gray background) items:

• Acidic Potion (Armor + Rags + Weapon) = Enemy loses 10 Armor for the battle.
  
• Ancient Vampire Blood (Blood + Ectoplasm + Flesh) = Minion restores Vigor equal to 15% of damage dealt.
  
• Bad Luck Mixture (Bones + Ectoplasm + Skull) = Enemy loses 20 Luck.
  
• Berserker Potion (Armor + Dust + Weapon) = Minion deals and receives 25% more damage for the battle.
  
• Breaking Potion (Armor + Flesh + Rags) = Target loses 10 Resistance for the battle.
  
• Cleansing Potion (Blood + Bones + Flesh) = Remove debuffs from target minion, then restore 10 Vigor.
  
• Cursed Flame Potion (Blood + Skull + Weapon) = All enemies lose 5% of Vigor and Sanity (bosses lose 1%).
  
• Daze Potion (Bones + Dust + Ectoplasm) = Enemy loses 20 Accuracy for the battle.
  
• Dead Leprechaun Potion (Bones + Heart + Weapon) = Minion gains +15 Luck and +15% Critical Damage for battle.
  
• Debilitating Potion (Bones + Flesh + Weapon) = Enemy deals -20% damage for 3 turns.
  
• Elven Ears Decoction (Ectoplasm + Flesh + Rags) = Minion gains +20 Evasion for the battle.
  
• Essence of Horror (Dust + Heart + Rags) = Minion receives +8 Dread for the battle.
  
• Essence of Wrath (Armor + Blood + Weapon) = Iratus gets 20 Wrath.
  
• Explosive Mixture (Blood + Heart + Flesh) = Enemy loses 20% (or bosses 5%) of max Vigor.
  
• Eyeball Potion ( Bones + Dust + Skull) = Minion gains +20 Accuracy for the battle.
  
• Fear Vial (Dust + Ectoplasm + Skull) = Enemy loses 20% of their maximum Sanity (bosses lost 5%).
  
• Magical Emulsion (Dust + Ectoplasm + Heart) = Iratus Spellpower increases by 20 for the battle.
  
• Mist Mixture (Dust + Rags + Skull) = All enemies lose 10 Accuracy for 2 turns.
  
• Potion of Bad Luck (Bones + Ectoplasm + Weapon) = All enemies lose 9 Luck for 2 turns.
  
• Potion of Denial (Blood + Flesh + Rags) = Remove all buffs from target enemy. Enemy also loses 10 Vigor and Sanity.
  
• Potion of Fallen Warriors (Blood + Dust + Heart) = All enemies lost 5 Attack for 2 turns.
  
• Potion of Vulnerability (Armor + Heart + Rags) = Target receives +20% more damage for 2 turns.
  
• Recovery Broth (Blood + Ectoplasm + Heart) = Minions recover 5% Vigor.
  
• Recovery Potion (Armor + Blood + Flesh) = Minion recovers 10% Vigor.
  
• Resilience Extract (Armor + Rags + Skull) = Minion receives -15% damage for the battle.
  
• Swamp Mud Decoction (Armor + Dust + Flesh) = All enemies lose 2 Initiative for 2 turns.
  
• Vial of Magic Essence (Ectoplasm + Heart + Skull) = Restore 20 Mana.
  
• Vial of Slime (Heart + Rags + Skull) = All enemies lose 10 Evasion for 2 turns.
  
• Wild Beast Decoction (Bones + Skull + Weapon) = Minion gains +8 Attack for the battle.