I have just finished two games of AH with "The Lurker" as a herald and he has basically done nothing to harm us. All he does is to give away free "clue tokens" and stamina/sanity when we were in need. Basically you can seal the last gates just by entering blood/sanity pacts with him and then trade your sanity/stamina for five power tokens to seal the gates. And power tokens are so easily spent that you hardly ever have any on your hands.
Maybe it's just me but he almost feels closer to a guardian than a herald and makes the game too easy. I have had no sensation of the "impending doom" that the other heralds provide, and thats what makes the game fun!
Or have I misinterpreted the rules in some way?