Runes are required to level up your stats. You can get Runes from defeating enemies or bosses. Each stat you level up increases your level by 1.

When you are unsure which stat to level up, go with the Vigor stat. Increasing Vigor will raise your health, making it easier to survive dangerous areas and bosses.

Elden Ring's combat system is dependent on stamina management. Even caster builds will have to do melee and dodge roll at some point. Making sure you always have enough stamina to block attacks, swing your weapon, or dodge away is a good investment.

NOTE: Players will be able to respec their stats after defeating Rennala, Queen of the Full Moon. Once she is defeated, she becomes an NPC. If you also have a Larval Tear in your inventory, you can respec your stats by talking to her and selecting Rebirth.