Spoilers: Game starts and his savage-orc buildings; no campaign ending.

Update 4 in the Badlands
Update 4 of the first Total War: Warhammer made Wurrzag free on the same day as The King and the Warlord, 20 October. The Grand Campaign line says Da Great Green Prophet was spied over-gyrating in the Badlands, uniting Savage Orcs of the Bloody Handz, and that he begins at Ekrund.
That is a Warhammer I start. It is not a description of his life before the campaign, and it is not the later jungle position. The free download is Steam's Wurrzag pack. SEGA's ownership guide also lists the first game, The King and the Warlord, and The Warden and the Paunch as routes. Any one of them is enough.
Update 6.0 and Cuexotl
The Gorbad introduction says the first thing a Wurrzag player notices is the move. His starting position is now the Southland jungles. The play page names the settlement Cuexotl, in the Central Jungle province. Opening a plan that still assumes Ekrund walks toward the wrong part of the map.
Both positions are game starts, and they are labeled by the update that used them. A campaign fought from Cuexotl is the current sandbox. It does not erase the Badlands line in Update 4, and the Badlands line does not tell you where the present patch begins.
Effigies, landmarks, and the prophet's title
Effigies of Gork and Mork is a building chain made for Wurrzag, at savage-orc sites. The blog names those sites, including Ekrund, his old start, Pahuax Statues of the Gods, and The Bone Gulch. Three landmarks are his to claim: Bone Nose Idols at Cuexotl, Bonewood Totems at the Springs of Eternal Life, and Iron Penz at Stormhenge.
The title on the page is Da Great Green Prophet. Big Waaagh! is his spell lore in the campaign, and Savage Orcs are the troops the buildings favour. A generic Savage Orc Great Shaman is described in the same blog as a conduit of Gork and Mork who fights with stone and shuns armour. That paragraph is the generic lord. It is not a private biography of Wurrzag, and it is not a second name for him.
Wurrzag: gameplay and availability · More character stories
Sources
- Total War: WARHAMMER — Update 4 — wiki.totalwar.com
- CA: Omens of Destruction — Gorbad — community.creative-assembly.com
- SEGA Immortal Empires ownership guide — support.sega.com
- CA: Update 6.0 — community.creative-assembly.com