How exactly did Boethiah outwit Trinimac?

I was under the impression that gods were more clever than that.

I am aware of how Malacath was made, but what caused it to occur?

I was going to answer and then I saw Lady N is reading the topic lol.

Nerevar?

Yay!

Question answered.

And then Lady Nerevar left without posting anything

Gods in TES aren't omnipotent beings. They're closer to the gods of the Greek/Roman pantheons in that they have human failings. In this case, Boethiah wasn't happy with Trinimac interfering with the Chimer, and decided to teach him and his followers a lesson.

Doh!
But as she said, the gods are not all powerful and Boethia wanted a certain group of followers.

How does Loki outwit most of the Norse pantheon? He's a trickster archetype. Boethia is a goddess of deceit, and murder. It's what she does.