Breaking the Wall
The Doctor looks like your average Joe he’s about 5’8 wears glasses and always has on a tie and button up shirt under his constantly pristine lab coat. He is a pharmacutical genius and has the ability to create most known drugs if he has the components on hand and the time to mix them properly.
His Wall is an extension of this ability he can turn almost any substance into some sort of drug even without the proper chemical components. His nickname among the GGP combatants is The Druggist because he has refined this ability to turn the wax in a filled hollow point bullet into any known drug while the bullet is in flight.