rare as a four-leaf clover
superrare
rarer than hens' teeth
semirare
rareish
rare as hen's teeth
ultrararefied
ultrarare
rare
rare as rocking horse shit
unique
uncommon
remarkable
antrin
geason
nonrare
sporadic
atypical
extraordinary
different
rarefiable
offbeat
rarefactional
hellacious
few and far between
seld
outré
superabnormal
commonplace
once-in-a-lifetime
exceptional
quaint
exotic
fremd
freakish
miscegenistic
miscegenic
unheard-of
miscegenative
weird
peculiar
nonrarefied
unrarefied
scarce
noneven
unmiraculous
supersubtle
queer as a clockwork orange
strange
one-shot