Devour Spell

Mastering magical energies, you have learned to siphon the power of magic to fuel your own spellcasting. When a creature you can see and hear, within 30 feet of you, begins to cast a spell, using a spell slot of 5th level or lower, you can use your reaction, to devour the targets spell. A spell slot of 5th level or lower is automatically consumed, replenishing a number of spell slots to the spellcaster equal to one half, rounding up, the spell slot used to cast the spell, and gains temporary hit points equal to twice the level of spell slot consumed.

At higher levels: using a 7th level spell slot devours spells of 6th level and lower. Using a spell slot of 8th, devours spells of 7th level or lower, and using a spell slot of 9th level consumes 8th level spells and lower.

Example: consuming a spell slot of 5th level restores 3 spell slots to the creature casting this spell. The spellcaster can choose to replenish a 3rd level spell slot or one first and second level slots; and gaining 10 temporary hit points.