Review Detail of HaremImmortal in Infinite Mana in the Apocalypse

I just started reading this novel There is no job change but MC becomes a mage because he can use magic. Then [strength stat] is physical strength, [vitality stat] is HP, if [focus stat] is Mana, then where does the magic power damage value come from? There should be an [Intellectual stat] ! Don't tell me that [focus stat] increases Mana and magic power? It's impossible because [focus stat] is unlimited so the damage should be very big too, but this damage is just normal. Hey author, have you ever played games or not?