a clan of Mountain giants believe a human mage can lead them to victory against the slightly superior Mist Giants of a neigboring mountain…their ancient cave drawings (think Bayern Tapestry on cave wall) tell them so…
What if potions and tonics had negative side effects? Potions of increased strength cause violent tempers, or damage joints. What if potions of dexterity caused tremors, or palsy?
What if they were addictive, and had withdrawal symptoms?
Could someone make a bad batch? No one use the brown strength potion!