[macphersonrants]

I'm also seeing Path/Book magic as the primary tool Constantine employs. The rules under Mortals With Supernatural Servants are certainly applicable to the setting. I would note that demons are subject to certain somewhat legalistic rules in some cases.

I can think of a few examples of spirits possessing individuals and giving them the sort of power boost you see in the Spirit Vessels section. I can't remember anything along the lines of a Spirit Warrior, but it doesn't seem like too much of a stretch.