na-adjective, noun
heartless; cruel; karmic retribution
Originally a Buddhist term for the inevitable results of past actions; in modern usage, it often describes a person who is cold-hearted or ruthless, implying that their cruelty will bring karmic consequences.
彼は因業なやり方でライバルを潰した。
He crushed his rival in a heartless way.
あんな因業なことをすると、いつか自分に返ってくるよ。
If you do such cruel things, it will come back to you someday.