A lucid dreamer.
The magician is he who defies what is thought to be impossible in his inner dream; thus, his outer world reflects that.
To master the inner world is to master the outer world.
The unawakened identify with the dreamed form; the awakened identify with the mutable substance that condenses into dreamed forms. The alchemists and magicians can transmute that substance at will — and thus, transmute the dreamed forms at will.
The clouds are that mutable substance — the rain is it manifesting — the fire purifies that substance back to its original form, heating, refining, and transpiring it back into the clouds.
This is why the masters balance water and fire.