Spell Eater

If you do not know the Counterspell spell, or have the Spellcasting ability, you gain the Spellcasting ability, and one third level spell slot, and learn Counterspell. If you already have the Spellcasting ability, you may cast Counterspell without using a spell slot.  Any casting of Counterspell with this feat that requires a roll suffers a -3 penalty to the result.  If you did not have the Spellcasting ability before taking this feat, the penalty is increased to -6.

When you successfully use the Counterspell reaction, you may choose to concentrate on absorbing the energy of the countered spell.  

If you end your next turn with your concentration intact and have not taken any actions on that turn, you regain a spell slot of the level used to cast Counterspell, or the level of the spell countered, whichever is lower.

You may use this ability a number of times equal to your dexterity modifier (minimum 1 use).  Each time you do, you must roll a dexterity check with a DC equal to 10 + the countered spell level. Add your proficiency bonus + your spellcasting ability modifier to this roll (use your CON modifier if you’re not a caster).  This DC increases by 3 with each use, and resets after a long rest.

You may choose to gain temporary hit points equal to the lower spells’ level instead, these temporary hit points vanish after 1 minute.