War mage

War mages, also known as battle mages, were wizards trained in the heat of combat, developing their abilities for the purpose of offensive use. Battle mages were dangerous to behold, deadly and capable of long-term combat survival. Battle mages could be as useful as a fighter in a melee or as deadly as a ranger from afar, depending on the wizard's individual preference.

"War magic? Does that make you a War Wizard? I've heard about them. They dress in purple, I think. But you're not dressed in purple. That's disappointing. Go change."

- The Xanathar

Abilities
In order to make themselves all the more lethal in combat, battle mages were trained to unleash arcane magic in an instant if necessary and with considerable ease. From the beginning of their training, battle mages were capable of striking a hindered foe with a blast of arcane power straight from their own body, which manifested as either fire, cold, or electricity. Battle mages also learned to focus their attacks in order to make them substantially more accurate. More experienced battle mages were also capable of unleashing any of their most basic spells reflexively when badly injured.

Battle mage spells universally enhanced the abilities of a wizard in battle. Relatively early into their training, battle mages learned the spell arcane rejuvenation, which served to heal battle mages, prolonging their effectiveness in combat. The more powerful closing spell was a devastatingly powerful blast of elemental energy that battle mages often saved for the finish, hence its name.