When you cast spells, the chaotic nature of your power will sometimes flare up and produce different effects.

Once per turn, the DM can have you roll a d20 immediately after you cast a sorcerer spell of 1 level or higher.

If you roll a 1, roll on the Wild Magic Surge table to create a magical effect. If that effect is a spell, it is too wild to be affected by your Metamagic. If it normally requires concentration, it doesn’t require concentration in this case. The spell lasts for its full duration.