master of whispers/margrid the sly

http://wiki.guildwars.com/wiki/Myste...tfall_quest%29

When I obtain one as a hero, how and where do I go to get the other? Do I have to beat the game first? Thanks.

after you beat the game you will have the opportunity to gain the heroes (from nightfall) that you didnt pick first (goren/nogru, jin/sosuke and mwhispers/margrid). They will be waiting for you in the throne of secrets (same kind of place as the divine path--you get your primeval armor here and your book of secrets)

http://wiki.guildwars.com/wiki/Throne_of_Secrets


so yes, you have to beat the game to get the others and once you do the final mission you can get the (easy) quests to pick them up.