I searched on WarDB and found all the Tier 4 Epic Quests starting points. Here's the links to all three. I haven't done them yet so you'll have to tell me if I got them right or not.

Tier 4 Epic Quests

Annihilation - http://war.allakhazam.com/db/quest.html?warquest=41124

The Ebon Flame - http://war.allakhazam.com/db/quest.html?warquest=45323

Time to Waaagh! - http://war.allakhazam.com/db/quest.html?warquest=20869