Level 9 Warlock
You may hold concentration on 2 spells at a time. A target may only be effected by 1 concentration spell from you at a time. If an enemy gets out of one of the spells and ends it or you drop one, this does not end the other. But if you take damage and have to roll to keep your concentration, you make only 1 roll. If you succeed, you keep both. If you fail, you lose both.