na-adjective, noun which may take the genitive case particle 'no', noun
extremely rare; super rare
Colloquial intensifier used for things that are very uncommon or hard to find, often in casual conversation about collectibles, events, or opportunities.
This card is super rare, so it's hard to get.
I'm happy I got to have such an extremely rare experience!
Compound of 激 (intense, extreme) and レア (rare, from English). A modern colloquial coinage.