liè huǒ gān chái
lit. intense fire to dry wood (idiom); inferno in a woodpile
fig. consuming passion between lovers
jí fēng zhī jìn cǎo , liè huǒ jiàn zhēn jīn
the storm put strong grass to the test, fire tests true gold (idiom); fig. troubled times test a faithful minister
to show one's true colors after a stern test