By picking a Single Boss target at any setting you will get the name of the boss you need to kill in the adventure window. Just attribute the name to the layout to the rare and cycle through the adventures until you get the one you need.
-The Accursed Sanctuary: Bazrael Firefall, Tazih the Eternal, The Cauldron Keeper
-The Ancient Aqueduct: Zukta Likae, Shinta Captain Yaem, Yunta Spiritmaster Efferael
-The Cauldron of Lost Souls: Gaz Commander Nezeim, Lokta Ancient Giddib, Lord Drigo
-The Chapel of the Withness: Poxtongue, Yaszil the Assassin, Arch Lich Xakasis
-The Drowning Crypt: Jinta Savant Grisk, Madakan, Oime Ugun
-The Foreboding Prison(Can fish): Uthiur the Fallen, Jinta Archwizard Zxiri, Shadowcreeper
-The Musroom Grove: Zukta Luiv, Aikyik of the Cauldron, Korta Archpriest Bhotea
-The Root Garden: Jinta Savant Grisk, Darta Berserker Tiriut, Airerick the Nightdweller
With the important caveat that, when requesting a dungeon, any of the last 5 dungeons that you have started will not be included in the possible dungeons you request next.
Goodurden!
