Even with the Scroll of Abraxus, which contains the password you must speak to Horus (who is blind, and knows friend from foe by this magic codeword, alone), you cannot get in. Speak the word as many times as you like, and Horus simply ignores you. Guess Blackrock deafened him, and KR blinded him? Heh (I like KR. I just can't run it smoothly).
Originally, the quest went something like this:
Make a new Necro, hear a story about summoning your daemon father (figuratively speaking) back from banishment in hell, cast Animate Dead on a skeleton in a crypt, talk to the reanimated dead guy, learn what to do, go to Luna, summon a horde daemon to steal the Scroll of Abraxus from that force field room in the north corner, read it, learn what to do, go tell Horus the password from the Scroll of Abraxus, gain entry, go steal the Calling of Kronus, go to summon Kronus from the dark pit in the east of Umbra, kill an NPC Paladin who suddenly burts through the silver gate there, attempt to summon Kronus, nothing happens, guess you must make the world a more evil place before Kronus can return, end of Newbie Quest.