Spellsurge

Through force of will, you can draw upon magic energies from within yourself to cast a spell without using a spell slot, but at the cost of gaining exhaustion.

To use this feat, on your turn, roll a saving throw for your spellcasting ability score with a target DC of 10 + your current exhaustion level. If the saving throw is successful, you can use an action (or, if applicable for the spell, a bonus action) to cast one spell you currently know and have prepared without using a spell slot. This spell can be cast at a spell slot level you would already have access to based on your class level up to spell slot level 6 minus your current exhaustion level. At the end of your turn, gain one exhaustion for each spell slot level used by this feat. If this feat raises your exhaustion to level 6, you immediately die at the end of your turn.

If the saving throw is unsuccessful, the Spellsurge does not occur, you gain no exhaustion, and you cannot attempt another Spellsurge until your next turn.

You must have an available action (or, if applicable, bonus action) to cast a spell using this feat.

You may not utilize unused spell slots to lower the exhaustion level cost for this feat. For example, you cannot use this feat in conjunction with an unused level five spell slot to cast a spell with a sixth level spell slot with the intention of only gaining one level of exhaustion. 

You cannot use this feat to cast a spell requiring a reaction.

You cannot use this feat on the same turn as another “surge” feat or ability, such as the Heroic Surge feat or the action surge class feature.