All spells become conjurations. Mortals can't work magic, they can only invoke creatures who can.
A spellcaster uses Detect Magic, and dancing serpents of golden-green fire appear writhing in the air and swarm to anything that detects as magical. He throws a Fireball, and a creature of elemental fire appears squatting in the area affected, burning all within it's enormous incorporeal bulk. Magic Missiles manifest as blue-green shark-like creatures of energy that 'swim' through the air to savage their targets. A Fire Shield appears as undulating tentacles of fire wrapping around the caster, and lashing out at those striking him. Skeletons brought to unlife by Animate Dead have tiny chortling imp-like creatures of ash and stench squatting in their ribcages, yanking tiny strings of mist that coil around the Skeleton's limbs, moving it jerkily, like some macabre puppet-master.
A spellcaster uses Detect Magic, and dancing serpents of golden-green fire appear writhing in the air and swarm to anything that detects as magical. He throws a Fireball, and a creature of elemental fire appears squatting in the area affected, burning all within it's enormous incorporeal bulk. Magic Missiles manifest as blue-green shark-like creatures of energy that 'swim' through the air to savage their targets. A Fire Shield appears as undulating tentacles of fire wrapping around the caster, and lashing out at those striking him. Skeletons brought to unlife by Animate Dead have tiny chortling imp-like creatures of ash and stench squatting in their ribcages, yanking tiny strings of mist that coil around the Skeleton's limbs, moving it jerkily, like some macabre puppet-master.