Line-of-sight from the spell caster is limited I hope they use the AowSM approach to global spell casting.
Other classes could have different global powers (and some spells) like;
Rogue: Gather intelligence, send assassin, poison weapons, bribe enemy, place trap, inform guards, bribe peasant, provide ale, place gold, ambush, etc.
Arch druid: Call animal, befriend animal, lure, distract, healing herbs, plant grow, wall of brambles, enhance animals, haste berries, undermine wall, summon will o wisp, etc.
Warlord: Inspire rage, courage, reposition, tactical withdrawal, determination, fire arrows, reinforcements; it’s just a flesh wound, personally trained, outmaneuver, etc.
Dreadnought: Land mine, exploding harness, clockwork bird. Indestructible, heavily armoured, secret weapon, repair machine, deploy defenses, special upgrades etc.
Theocrat: Inspire faith, devotion, hope, bless, heal, bolt from above, strength in numbers, summon devotee. strength of a lion, the chosen one, summon avatar etc.
As a mighty sorcerer casts a spell over a great distance, other classes rely on different measures to influence and control their domain.
Works well with Unknown250 Fortresses idea and JeanLucPicard and others class specific buildings.