SureAI

There should actually be three KEYSTONES in the first ruin (near Furtsanden). Have you forgotten to take them?

My God! I came back to the cellar in Gilliad (where I found the first key) and didn't find anything else.

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I also went to
the first crypt behind near the wall the scarecrow points to, but didn't find anything...

I went there 3 times, for God's sake! But you are right! They are right there! Found them on the third time! Damn, those are hard to see.

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And guess what! I went to the 3 places, killed all undead all over the place, then when I reached the Darius Temple... I am also missing the key! Aaaarrggyhhh! It must have been somewhere in the last crypt!

You can return there to take the keystone.

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The keystone is placed on the table with the memo ("Darius' Temple") into the room with armor ("Protective Armor of the Templars").

Yes, I found them. Thank you.

This quest is both so great and at the same time so hateful, because the damn keystones are so hard to see. At least they were for me!