God mode is when no one can hit the item phase that begins at 3%. It last for a period of time. The item tester needs to periodically use items to see if god mode is over. But he needs to work fast before god mode starts up again.
That is also a good question So much must be learned about these strange epic battles and their possibly conflicting religious viewpoints
God mode, is when the eb gets to the "half-awakend state" phase which is sort of phase 4/3. Then, if nobody can hit items succesfully (if one isnt able to, nobody can), its called GM/godmode. This period lasts 5-8 minutes. After that, you can start draining the items. 5 locust swarms and 8 holy wrath + angels of light. Make sure only one person uses pots/checks for god mode, since you may miss the sweet spot otherwise