What is the "grand cross"

Ok so i was doing a ritual that was something to do with becoming a living devil, lake of fire workings and infernal alchemy

I was seeing visions of my demonic body and current
I seen my self dragons and devils in the lake of fire going through all existence i heard something like this “you are iniatated in the grand cross”
Or thoughts about the grand cross i dont quite remember. What is the grand cross?

From what I can gather, this: https://astrostyle.com/aspects/grand-cross/