してやるからな

I'll make sure to …

→ 為る

phrase Rare #45,300

I'll make sure to … An emphatic, informal way to declare that you will do something. The tone can sound determined, threatening, or condescending.

JA: もし戻ってきたら退治してやるからな。

EN: If you come back, I'll make sure to get rid of you.

I'll screen it no matter what!

— ニュー・シネマ・パラダイス (1988)

I promise I'll make all of you like you were before.

If you come back, I'll take you down.

— レミーのおいしいレストラン (2007)