Kill it./Kill them./Show them who's boss.
These expressions are used before taking an important test at school or playing in an important soccer game, etc.
It can be said in Korean as below.
실력 발휘해.[sil-lyeok bal-hwi-hwae]
실력 [sil-lyeok]: skill, ability, talent
발휘 [bal-hwi]: demonstration; display; exhibition, (verb) 발휘하다[bal-whi-ha-da]
