Magician of fire and ice

2000 years ago a man broke the chuckles of the world of magic and reached a level that made the gods feel the threat of competition... Envious of this human the gods sought to destroy him and a battle between him and the gods went on for 7 days and 7 nights destroying 5% of the earth above the water. And the one of the three ultimate spells of the heaven was used to stop the human... The spell was meant to destroy him but the spell was cast without the complete preparation so the human managed to survive but woke up 2000years later with no memory of what happened and in the body of a 6year old kid.....