On Page 15 there's a mage like miniature at the centre of the army example.

Somebody knows who that is?

It would appear to be Kyndrithul, one of the more recent bosses/lieutenants from Descent 2nd Edition. It's certainly similar to the miniature for that game.

From the upgrade pack maybe ?

https://www.fantasyflightgames.com/en/products/runewars-the-miniatures-game/products/waiqar-infantry-unit-upgrade-expansion/

No, it's not the Necromancer or any other figure from that pack, it's a different model.

It's very likely a Descent mini see here , but that link was already posted by maxam on your other thread of the same name.