Vis crystal
Aqueous Crystal.
Crystals are very important. they are six kinds of crytals:
Fiery (fire), Aqueus (Water), Earthen (Earth) Vaporous (Air), Tainted (Dark) and Vis (Magic).
Crystals in majority depend on biome, Fire/dessert Water/swamp Earth/Mountains Vis/in areas of vis air/Jungle tainted/In areas of taint
Putting down crystals does not effect the Aura but destroying them will, tainted will boost the Aura and others will decrease the Aura.
