Once they had been ruled by Kings. Men with shining armor, riding griffons and winged horses into battle. Nobility and birth right and divine right had been the sources of power.
Now magic is the source of power and is power. Rule by those who can because they can and no can stop them. Apprentices at the front lines, journeymen casting from the back, and masters ruling far from battle.
The wind shifts, there is movement along the enemy line, and they wait for the diviners to make the call.
“MEN!” and they grab their firearms and spring up to the parapet of their trench, firing on the shapes they see slogging through the mud. Thirty seconds of shooting, black silhouettes in gray fog coming closer, before fireballs begin to fall and the enemy withdraws.
“BEASTS!” and they grab their pikes and spring up to the parapet of their trench, thrusting the points forward to become a wall of spikes. Once beasts had meant manticores, hydras, and wyverns. Now they were the products of magically quickened breeding, hybrids of every predator that could be found, confused amalgamations which collapse and split and melt when they die.
“FIRE!” and they rush to their designated bunkers, keeping their heads down and not looking at the second suns falling from the sky.
Worst of all is when no call comes, when the diviners begin to babble and all unburied corpses join them. Someone has become desperate, a breakthrough is needed, a curse is on the wind. Hold your sacred trinkets tight and pray.