the 3 dark crystals

[sirdeathmage]

i found the dark crystals from the big praying mantis near the atainius lagoon and the one given by jonas's dragon mount but i dont know were the third one is and i cant pass the copper knight infront of the magical cave of fire

[sirdeathmage]

aswell as how do you find the completion library

[Anima Zero]

3rd Dark Crystal is in the Earth Caves in the dark section with the Armor of Darkness, Truth Glass, and Moon Stone in the first portion of the cave before you reach a bridge.

At that bridge, keep an eye on the pillar with a purple-ish hue on your right.  You should notice solid ground near it which you can land on.  There's only one lone enemy between you and the Dark Crystal.  Do keep in mind that you'll need a way to warp out after getting this though.

As for the library, it's near JDO, the guy selling stuff outside in Central Village.  Look for three tall pillars standing upright next to each other right behind him.  The middle one is fake and you can walk through it into the library.