1 to use an opponent's own methods to obtain retribution (idiom, from Song dynasty neo-Confucianist Zhu Xi 朱熹); to get revenge by playing sb back at his own game
2 to give sb a taste of his own medicine
任其自然
rèn qí zì rán
1 to let things take their course (idiom)
2 to leave it to nature
3 laissez-faire
作茧自缚
zuò jiǎn zì fù
1 to spin a cocoon around oneself (idiom); enmeshed in a trap of one's own devising
2 hoist by his own petard
优游自得
yōu yóu zì dé
1 free and at leisure (idiom); unfettered
儿孙自有儿孙福
ér sūn zì yǒu ér sūn fú
1 younger generations will do all right on their own (idiom)
冰炭不言,冷热自明
bīng tàn bù yán , lěng rè zì míng
1 ice or coals, whether hot or cold goes without saying (idiom); fig. sincerity is not expressed in words