Base Class: Monk
Your petrified stone body is veined with an ancient arcane crystal which naturally reflects, traps, and refracts magic. With practice and focus, these crystals natural properties can be incorporated into your martial arts to turn an enemies spellcasting to your advantage.
Level 3: Primordial fist
The crystals composing your body hold an ancient raw form of magic, unrefined and unstable. Whenever you roll initative, you may also roll D10 on the primordial magic table to determine the damage type of your unarmed strikes. This effect fades after 10 minutes.
Additionally you may cast Absorb elements as a reaction a number of times equal to your proficiency bonus per short rest. Doing so also changes your primordial magic type to the type absorbed.
Level 6: Spell sink
Your growing attunement to your crystalline structure has allowed you to fully absorb the force of some incoming spells.
By expending 2 focus points you may cast counterspell as a reaction at its lowest (3rd) level
Level 11: Spell steal
You've mastered the ability to not only absorb, but fully redirect incoming spells.
By expending 3 focus points you may intercept a spell, fully absorbing its power. On your next unarmed strike, you may add the effects of the stolen spell (damage, conditions and all) to the damage of the unarmed strike.
Alternatively you may choose to hold the power for a future attack, or even use this feature in succession to stack multiple spells into one punch. However, you will need to pass a Con saving throw of [10+ the level of the highest spell held] with your attack. On a fail, the damage is split between you and the target.
Level 17: Primordial form
You have advantage on saving throws when targeted by a spell.
Additionally, you automatically have resistance to the damage type associated with your current Primordial Fist typing, even if you have not cast absorb elements.