Polus has another task for you. This time no Necromancers (cross my heart and hope to die). There is a problem with some field researchers at the Ayleid Ruin called Vahtacen. The project is under the direction of Irlav Jarol, but he's been so tied up with other matters that he hasn't been able to deal with the problem and everything is stalled out. So why not be a good Evoker and pop upstairs to see if you can give the old fellow a hand.
Jarol is upstairs in the Council Chamber (if you wait a few minutes, he'll come downstairs). He has received a report from Skaleel, the head researcher, about a blocked passage. Go investigate and then report back to him.
Before you leave for Vahtacen, make sure that you have a Frost damage spell, scroll or staff (Cold Touch and Snowball are both Novice-level spells). If you don't have one, you can try to pop upstairs and lift the Staff of Hrormir from the Arch-Mage's quarters. It could very well get you kicked out of the guild, so it's not recommended, but it is an option if you're truly desperate. You can make your life slightly easier by being able to cast a Fire-based damage effect, a Damage Magica effect (Drain or Absorb effects won't work) and a targeted Fortify Magica effect spell, but it's not necessary. You already have a Fire-based spell (Flare and possibly Weak Fireball from the Skingrad Recommendation quest). Sever Magica is an Apprentice-level spell, but you may have picked it up on a scroll somewhere. Fortify Magica is Journeyman-level and is probably beyond your abilities at the moment. Moreover, it's cast on yourself - you need a targeted spell. Don't worry if you don't have it, we can work around the problem.
Vahtacen is more or less southwest of Cheydinhal. Just travel to the stables and then follow the road south. When you reach the end of the road, just follow your compass marker. Except for possible overland encounters, there is nothing to fight until you solve the puzzle, so don't worry about combat at the moment. Go in and talk to Skaleel in the first big chamber.
Their progress has been blocked by a pillar that they can't get past. The mages who have tried to use magic on it have been zapped, so they think it's a lock of some kind. Go down and talk to Denel to get the current situation. Denel isn't much more help. There are some Ayleid runes in the chamber with the pillar, but he can't translate them. Perhaps if you could find an Ayleid reference of some sort, he might be able to do something. Go into the room and you'll see four Dark Welkynd Stones. If you haven't run into these before now, they like to zap you. You can't sneak past them and you can't damage them. The stones in this room aren't doing anything at the moment, but they are obviously the source of the zapping for the other researchers. On the wall behind each stone are some runes. Starting on your left as you walk in and continuing clockwise:
Go back up and talk to Skaleel about the Ayleid Reference and she'll give you a book, "Ayleid Inscriptions and their Translations". Right there on the first page is "av molag anyammis" - "from fire, life". Denel will be able to help with the translation of the rest. It appears that you need to cast particular kinds of spells on the central pillar and, equally importantly, in the proper order.
Before you start, check out the crate next to the table near Denel to find some scrolls (awfully thoughtful of the devs, don't you think). You'll find one scroll of each type needed, except for Frost. This is where the "slightly easier" comes in. Any effect that you can cast for yourself means that you get to keep a scroll rather than use it on the pillar. It's also why you must have a Frost effect - there isn't one in the crate.
So, in order, cast the following at the pillar. I recommend saving first in case you make a mistake.
With each successive spell, the pillar will split apart, finally revealing a doorway into the rest of the ruin. If you get one spell wrong or in the wrong order, be prepared to get zapped by one or more of the Dark Welkynd Stones. Get it wrong on the last spell and you'll be hit by all four (you'll also lose your only scroll with that effect). What now? Well Denel and Skaleel insist that since it was your solution, you should get the credit for anything that you might find down there, so you're on your own (researchers...they're behind you all the way - literally).
Vahtacen is very hard to get lost in. There are, however, three traps in here that show up in other ruins. The first one is a section of floor that drops down onto some spikes. The second is a section of floor that rises upward into some spikes. The third is a passageway with swinging blades. You can circumvent the first two by running across the corners of the trap. For the third, timing is everyting. And just to make life more interesting, there are Dark Welkynd Stones in the first two locations, Resist Frost or Frost Shield are recommended.
Just keep going until you get to a room with a raised platform in the middle of the room. Head up the stairs at the other end and press the blue button on the right at the top of the stairs. This will raise a set of stone steps on either side of the center platform. Reaching the top of the stairs causes some leveled undead to spawn in the room below. Take care of business. At the top, press the button on one of the corner pillars to raise the cover and reveal an Elven Helmet, which you should snag. This also opens a secret door in the center of the back wall.
You now have a couple of choices: either go back the way you came, use the shortcut exit in this room or press on forward to the now-open section at the rear of this large chamber. I'd recommend going forward because there are a couple of Ayleid chests that you'll miss otherwise. You'll need a few lockpicks or approprite Open spells because the containers are locked. You've also got some more undead back there. The exit from this section will put you back near where you entered from the pillar room.
While the way you came is probably clear, there is some unexplored territory (and more goodies and undead) if you use the locked gate in the big chamber. Your call. If you decide to take this route, you'll come out in the corridor about halfway between the stairs and Delen. Talk to Skaleel and she'll tell you to take the helmet to Irlav Jerol, who will be suitably impressed with your accomplishment. Then talk to Polus for your promotion and a nifty robe.