Large 12 is a low-order quasi-number. It is independent of ZFC + GCH, but its existence is implied by the Ganzer-Schmidt large cardinal axiom extensions.
It is in some ways similar to 12, but it is only weakly a number. A large 12 is semi-provable and thus is inconsistent with most most general ordinal axiom schemata, in particular it causes a super-contradiction with the Czilassi-Donver schema.