I believe they should be at planet level and mhs+ to sub-rel.
Gabriel is superior to Leviathan, who can "reduce the planet to ashes", and Laura's statement that the Forgotten One's power can " reduce the world to ashes". It might be higher if reducing the planet to ashes might yield higher. Gabriel as Dracula kicked Zobek's ass who could create a device capable of forming a solar eclipse.
Can react and block Carmilla's and Nergal's lightning. Both come out and travel at similar speeds to the Lightning spell in Fable. You even have Light magic that Dracula and any Belmonts can use. This Light can reflect from mirrors so that it might be legit Light. The power source comes from an ancient god named Pan, who keeps the order of nature and brings balance to the world. Unfortunately, her death left the planet with natural disasters.
Notable hax consists of BFRing via sending beings to his mind castle, which is his pocket dimension. With Chaos, Claws can burn souls directly. Turned the Forgotten One to ashes just by waving his hand. Can use mind control, possess people, and slow down time.