A link between eras.

The Krigans cannot be demons. I'll explain. The answer lies in their physiology.
Krigans are essentially parasites (see the movie "Independence Day"). Their goal is to destroy all life and drain the planet's resources. Conquest doesn't interest them at all. See the Krigan guide in Might and Magic 6.
Inferno.
1. They cannot live in the world of humans!!!!!! (Read the castle description)
2. They don't need the world of humans, neither as a resource nor as living space.
3. It's not clear at all why they attacked?????????
4. The atmosphere of Ashan doesn't suit them. Because of the low temperature;)

In general, don't interfere with them.