Strength potion

Strength potions can be made by a member with 12 Herblore by mixing tarromin and limpwurt root in a vial of water, giving 50 Herblore experience.

Additionally, if you take a limpwurt root and red spiders' eggs to the Apothecary in Varrock, he will make a 4-dose Strength Potion for you for 5 coins. You don't need any Herblore level for this.

Members with 130 attack and strength combined can enter the Warriors Guild and buy strength potions there.

Strength potions temporarily raise your strength level by 12%. They are the only potion available to non-members. If you add roe to a 2 dose potion it will become a 2 dose strength mix which heals 3 hitpoints, adding caviar instead will increase the health gain to 6 hitpoints.