Enduring Spell (Drezno)

You have practiced maintain the concentration on spells in the midst of combat to an extent of exhausting yourself to death, learning the technique that allows you the following benefits:

• You have advantage on Constitution saving throws that you make to maintain your concentration on a spell when you take damage.
• When a spells duration of a concentration spell would end from its full duration expiring, you may push yourself further to maintain its effect an extra duration equal to its normal duration, by gaining 1 level of exhaustion.