'Tyrant Overlord Baal' is the last god you will fight (until you beat him, because he regenerates). You can fight gods on the 'Gods' tab of the 'Fight' section. He is very strong and it will take a long time to level up enough to beat him. My attack stat was in the hundreds of septendecillions when I was able to do it, to give you an idea.
The basic strategy is to:
- build clones (happens automatically)
- use clones to fight monsters, raising your power levels
- use clones to build monuments, raising your power levels
- use clones to fight gods, raising your power levels
- use god power from beating gods to increase your 'creating speed' and 'building speed'
- rebirth when all numbers on the 'Rebirth' tab are green and significantly higher than now
- rinse & repeat, getting further and further into all steps