Tracing magic sigils in the air, you ward yourself from a certain element you choose when you cast the spell: acid, cold, fire, lightning, or thunder. 

For the duration, when you take damage of the chosen type, you can gain resistance to the damage from the triggering effect (no action required). The spell then ends.

Starting on your next turn, you must use a bonus action on each of your turns to maintain the spell. If you end your turn without having done so, the spell ends.