Potions are not emergency decorations. They are temporary cards you can choose to draw at the exact moment they matter.
Use potions before the fight is lost
The best potion often prevents 15 damage, not 3 lethal damage. If a potion lets you kill one turn earlier or block a major hit, use it.
Buy potions for planned danger
A shop before an elite or boss is a good reason to buy a strong potion. Buying a potion with no dangerous fight ahead is less urgent.
Empty slots are wasted value
If all slots are full and a new potion drops, be willing to spend or replace the weakest one. Hoarding a low-impact potion can block a run-saving reward.