Spells/CounterSpell

If you're countering the opposing school of magic, you treat the incoming spell as if it were one circle more potent than it actually is.

-- Neph

Which incidentally means that no-one can Counter a Solar-Circle Spell but a Solar and no-one can Counter a Void-Circle spell but a Deathlord or an Abyssal.

Or a Celestial using the Mantle of Bridgid or other similar effects ...

Or a Sidereal Martial Artist using Spell Shattering Palm.

Or an Infernal Exalted like Dukantha from Blood and Salt.

hmm. Actually there seeem to be lots of beings that can counter Solar Circle Sorcery. Possibly more than the number of Solars that can cast Solar Circle Sorcery.