Who are they?

Gul’dan of the Stormreaver Clan was the apprentice of Ner’zhul, the spiritual leader of the orcish clans of Durotar. Ner’zhul initiated his race’s pact with the Burning Legion, but began to question his earlier judgement. When he tried to bail on the arrangement, the ambitious Gul’dan was there to usurp him. As punishment, Ner’zhul would later be transformed into the Lich King, while Gul’dan continued to wield and master his newfound demonic powers.

Auriel is the archangel of hope, one of the five supreme angels that command the armies of heaven. She is perhaps Tyreal’s closest ideological companion, standing alongside the archangel of justice when he voted not to destroy humanity, believing that there was a chance humanity would be a great ally, or at the very least not destroy all of existence. 

There is no current release date for the two heroes, other than they’ll be coming ‘in the next few weeks’.