A well roleplayed Marut is great. As a CR 25 construct, it's going to be enforcing a universal law, such as attempting to stop a world ending threat.

It's primary aim is normally to planeshift it's quarry to court, rather than kill them, and may even prefer not to kill those who come between that goal.

Here's The Monsters Know What They're Doing's blog post on them. It really telegraphs how helpless a targeted creature is to them.