I was going to embed the spell into a gem, not make it a potion: gems are more his style, which also gives people the option to "lose" the item if they want extended peril and no rescue, or if they say want it one day then never again etc. Easier to get rid of narratively if it's an item, and permanent enchanting is usually not to a person.

How about 5 uses of 5 minutes per day, with at least a five minute cooldown between (to allow for oops I used it but then got smacked while I couldn't) but on the fifth use the item requires a 12 hour period to recharge? Makes it usable several times in one battle but not long enough for people to never be splattered in the ground ever again.