There are only six combinations that you can make: Mist Runes (from air and water), Mud Runes (from water and earth), Dust Runes (from air and earth), Smoke Runes (from air and fire), Lava Runes (from earth and fire), and Steam Runes (from water and fire). To make a combined rune you will need the two talismans (one of each of the ones needed to make it), a rune (can be either one of the two types of elements), and the rune essence. You will need to go to the altar of the element that you DIDN’T choose for the rune.