Every draoi has three orbs on keys 1, 2 and 3. Sign any three of them for a spell, ten in all. Stand in elemental terrain and the terrain can be the third sign, even an element you do not have: that is how you reach spells outside your ten. Sign all three yourself in terrain whose element is in the spell and it is empowered. Each spell has its own short cooldown before you can cast that same spell again.