[Baalz]

Reverse communion works best with fire or earth spells because it's a lot easier to cast the appropriate buffing spell. If a master casts Earthpower/Phoenix power then power of the spheres it raises lowly F1/E1 guys up to level 3, which lets you cast the fun stuff like falling fires/blade wind. Air and water are a bit harder as you'll often be looking at just the 1 level bump from power of the spheres...and not even that if you're doing a sabbath with no available astral.