The Ancient Altar, which is used for praying to The Huntress, is located through the magical green barrier in the River Tunnels under the town of River's Rest, near the magical blue barrier used to teleport to the Citadel.
Wonders of Elanthia Historical Discussion
This story has been told by Rajegal the Human Scholar.
"I well recall my first venture into these River caverns. Yes, now... come along, one by one. It's a bit narrow in here. You see, as a young fellow, I had a bit of trouble with the local jungle's trolls. Namely, I discovered myself prepared for their stewpots one day after an otherwise pleasant jaunt. My, I hate trolls. Near on the edge of death, I made my way here, for I'd heard rumors here of an altar to vengeance. A magical green barrier guards the entrance to Her shrine here, and I had not yet discovered the secret of passing through it. So I prayed to The Huntress and railed at Her at the same time, for She seemed not to hear my calls for vengeance against the trolls that had so nearly ended my brief existence. And, like a fool, I chose to seek vengeance against them on my own. I returned to seek vengeance against the trolls. It did not go well. They took my hand, first, and forced me to watch as they turned each and every finger into stew. It was their plan, I presume, to keep me alive for days, and use me for food bit by bit. Yet as they rested, something wonderful and terrible began to occur. First, it was just a bubble of activity on the back of one troll. Then a twitch here, a chance flexion there. Within minutes, however, I saw The Huntress's hand at work. Limbs began to erupt where there should be none. Organs clearly out of place began to sprout from their very skin. She had turned my lost hand into a weapon, a poison that sent their prized regenerative abilities out of control. And so I left them there, undying but unable to move. I can only imagine that Her merciful hand ended those creatures eventually...either that, or we've got some blubbery, gelatinous troll-creatures oozing about."
Entering the magical green barrier
The magical green barrier is normally closed, and can only be opened magically. In order to open the barrier, a number of first-level spells must be cast at it from different professional base circles. Although there may be several successful combinations, apparently Prayer of Holding (301), Natural Colors (601) and Blood Burst (701) is a sufficient combination, as shown below.
[River Tunnels, Barrier]
The humming, glowing barriers that make up the north and south walls immediately grab your attention when you enter this chamber. The amount of mana involved in constructing and maintaining two such barriers throughout the ages staggers you as you think about it. You can even feel the ambient mana in the room bathing you in its flows. You also see a pale golden cougar, a magical blue barrier and a magical green barrier.
Also here: Mister Dhat, Grornak, High Lady Nihrvanah, High Lord Durakar, Arinasi, Event Coordinator Astru, Dhairn, Squire Legionnaire Hanshayr, Uthenegal, Draithe, Lord Kamter, Lady Jersea, Lord Roblar, Aiya, Chancellor Khiya, Gargamish, Kirael who is sitting
>Astru makes a nearly imperceptible motion while whispering a soft phrase...
You trace an intricate sign that contorts in the air while forcefully invoking Blood Burst...
Your spell is ready.
>Astru gestures at a magical green barrier.
The barrier soaks up the magic of Astru's spell and seems to glow more brightly.
>cast green barrier
You gesture at a magical green barrier.
The barrier soaks up the magic of your spell and seems to glow more brightly.
>Aiya chants a reverent litany and clasps her hands while tightly focusing her thoughts...
>Aiya gestures at a magical green barrier.
The barrier emits a high, piercing shriek and opens slightly; for how long you are not sure.
>go green barrier
[River Tunnels, Ancient Altar]
Having made it past the barrier guarding this room, you are treated to the sight of an ancient altar that dominates most of the available space here. The magic of the barrier appears to have kept this room completely dry, as is evidenced by the musty, ancient smell of the air that has been trapped here for centuries. You feel a bit unsettled here, as if someone is lurking in the shadows ready to strike at your back at any moment. You also see a magical green barrier.
Obvious exits: none