Its situational and rather tricky ruling for the model/s as there aren't any other hero mounts in the game.
A couple of things I could think of
- Fate would only be able to used on the Warg and Azog individually as they are still to separate heroes with separate wound profiles.
- Will can be used interchangeably to resist magic as it targets the entire model. I see this goes for courage tests as well as only one test is take for both the rider and mount together.
- other models wouldn't benefit from a heroic move/ march by the white warg unless they themselves are a warg (see Pack Master rule), however Azog if mounted on the White Warg would still be able to move about by himself on the warg as they move as one.
- Azog still benefits from a heroic combat/ heroic strike called by the white warg as they move/fight as one. other models wouldn't as per Pack Master rule.
So essentially you have "One" mounted hero with 6 Might and 4 Will making mounted Azog one of the most devastating heroes on the charge in the game.
what is it like 8 attacks he can put on a single model in combat if he wins on the charge while mounted?
Screw Sauron I gotta get me an Azog. In fact now that I think about, Azog could probably rather easily beat Sauron with 6 might points up his sleave wounding on a 3+ LOL
That's just what i can think off the top of my head at the moment I hope it helps Ted.