They are those purple ones with the devilite heads above them before the boss room's group button.
1: Who/what left them there?
2: Are they in Shadow Lairs?
Because next year I want to save 4 shadow keys (maybe 5 if the new boss has one) to see the SL bosses wearing elf hats.
EDIT: clarification added.
No. I mean those purple ones before the boss rooms with the devilite head above it -.-
I imagine they were installed there by the tech knights, just like beast bells.
The Codices was something that was requested as an ingame reference book for monsters quite a few times on the suggestions forums, which to most people replied "Dude just look at the wiki".
I guess this is Three Ring's way of satisfying those people without spending a lot of precious developer time in addition to clearing up the confusion about how to defeat bosses.
But that's the fun of it!
When I was still 2* (long before we had missions) I was a bit confused on how to beat the Snarbolax until I saw the bell in the middle.
Then when I was 3* (missions) I had no idea how to defeat the Roarmulus Twins until I thought to shoot their rockets at each-other.
If that's not proof enough, I always tell my father I'd rather learn something by myself as opposed to having the direct answer and secrets just given to me. It's that feeling of accomplishment that you've done something good and will supplement you in the future.
If I know I can't do it from the bane of my own wit then I'll ask for a step-by-step guide followed by chances for me to actually do it.
Back in my day, Vanguards were constantly rerunning lame bosses to get guild boss statues. They did all the work for the first 3 bosses, which was about as long as the general frenzy lasted.
Also, darkfire vanaduke wasnt wearing a christmas hat when i last went there this winterfest... Just saying this so you dont save for the keys for a year to find the SL boss without the hat, but maybe that will be different next year.
Now this just does not make sense. If the tech knights leave it there...HOW COULD THEY POSSIBLY TRAVEL DOWN TO VANADUKE JUST TO PUT A CODEX THERE AND THEN COME BACK UP LIKE NOTHING HAS HAPPENED?!
If you've actually read what they said, Alpha Team leaves them.
No, in Shadow Lairs, you get something called an "Echo Stone," an Artifact that, when Activated, causes voices to talk to you.