Focused Mind

Maintain concentration on two spells, by gaining exhaustion.

You gain the ability to maintain concentration on two spells at your own expense. At the end of your turn, you gain one level of exhaustion. This exhaustion from arcane forces wreaks greater havoc on your body than normal means; spells and effects can remove one level of exhaustion, but you can only recover from one level per day. 

Additionally, the combined level of spell slots you spend on the concentration spells must not exceed your level ( a level 10 character can concentrate on one spell that used a level 6 spell slot, and one spell that uses a level 4 spell slot). Note: this is based on the spell slot used, not the level of the spell itself.