One of the mechanics that gives Massive Darkness the feeling of a living dungeon is the idea of wandering monsters.
You have the various minion in each room, along with minions, and wandering monsters (bosses) that randomly spawn at points in the dungeon and wander around looking for adventurers to thump.
These wandering monsters not only bring more wounds, but also a number of unique dice based abilities that one has to navigate.
Enter the Ogre Mage.
Of all the core box wandering monsters, second to the Hell Hound which is an amazing sculpt, is the Ogre Mage.
Tactically he brings both close combat and ranged magic attacks, with the chance for a power up on both a gem or a bam. At 4 wounds he isn’t the toughest in the box, but with his ability to heal from ranged attacks- especially magic he tends to stick around and take a beating- as expected from an ogre.
And that is before he uses any magic items that spawn with him.
Tactically of course, as with all roaming monsters, depending on where they spawn and how wandering the dungeon is- do you engage them or run away.
I find with the Ogre Mage, one has to engage given the combination of movement, magical attacks, and healing.