I've gotten 3 pieces of the set from the various Revenants, but I'm still missing the armor itself. I recall someone mentioning that I'd have to solve the puzzle in the elven ruins involving that jug of water and the fountain to get it, problem being that I can't figure it out.
I've read the order of events that I'm supposed to follow in my journal, but I'm not sure if I'm supposed to perform them all at the fountain itself (tried this and the right combination didn't seem to come up) or if there's some other altar for the first few steps as mentioned in the journal.
I noticed an altar slightly further down in that room with the bookshelves, but when I clicked on it all that happened was that a message came up saying that it looks as though I can place something on it, but that was it. Oh yeah, and I removed the jug from the fountain and have filled it with water, but I can't seem to place it on that particular altar so I'm not sure if it's the right one.
It's all in the same room with the fountain. The tablet is literal up until the last part.
You take the jug, and fill it with water. Then you place it on the altar. Then you kneel and worship it. Then you take a sip, then you take it back to the fountain and pour it out. That last bit took me a second, because the tablet literally has the priestess standing in the water with it overflowing from the jug.
Inside the room that unlocks is your last battle for the Juggernaut chestplate.
You're only the millionth person to ask the same question...
The altar in the room with the books is related to the Arcane Warrior quest, not the Juggernaut quest. The altar you're looking for is in the same place as the pool of water where you get the jug. You don't even need to leave the room. Try using the TAB key to find it if you fail to spot it yourself.
--- "Go out, find a girl. Doesn't matter who, as long as there's no pants involved. "