Luranea

Physical Characteristics
Quite large, especially for a spider. Rotund bodies with large mandibles. Appear to be fully crystalline themselves.

Behavior
Aggressive towards humans. Whether this is out of terrirotial behavior, protection of younglings or a hunter's instinct is unsure. They stalk their prey while invisible and strike with their mandibles, injecting a crystallizing venom that coats the afflicted part of their victim in a thick layer of pale blue crystal.

Field Notes
Perhaps their aggression was the result of the students trespassing into their nesting chambers; there is reason to believe they have been encountered before their attack and kept quiet, just invisibly skittering around.

Appearances
The Luranea appear in episode X of season one, where they appear out of fucking nowhere and assault the party, nearly killing Loyd in the process, though his +30% near-death intelligence buff helped them get out of the ensuing situation.