The mana crystals (alternatively referred to as Blood Crystals, Defense Crystals, Scrying Crystals, Bloodgem Crystals, bloodgem, or Arcane Crystals) are blood elf creations used to store arcane energy. Unlike the fel crystals, they are typically crimson in design.
The crystals have multiple uses. In addition to storing arcane energy, they can protect blood elven towns and outposts by empowering a large dome around them, interconnecting with other nearby crystals to increase the shield's radius. This dome is resistant to both physical and magical attacks, while the crystals themselves can act as a natural insulator of substances such as lightning. They can also be used offensively: as seen at the Dawnseeker Promontory, the crystals (if moused over in-game, these are named the Defense Crystals) possess magical anti-air attacks capable of striking aerial enemies down at mid-to-long range. They can also be modified to serve as arcane wards to dissuade intruders.
The crystals require some degree of mana input to be fully charged. If siphoned using a smaller , the crystals can give the user a charge of arcane energy to boost their abilities for a limited amount of time, though if a blood elf undergoes this process, the exposure to raw arcane energy augments the elf's innate addiction to magic and is considered hazardous. Subsequent appearances of the crystals (such as on the Isle of Thunder) are utilized on the inverse principle: the blood elves channel magical energy into the crystals, rather than out.
The crystals can also be used for scrying purposes; the largest crystal in the Dawkseeker Promontory is explicitly named the "Scrying Crystal," and overlooks the entire Isle of Thunder. The crystals can come in smaller forms (the aforementioned bloodgem shards; some elves also mention possessing smaller mana crystals to draw upon directly) too. Unstable mana crystals, if not handled properly, could explode with enough force to blow a hole into a city's walls.
In order to fight their magical addiction, many blood elves started draining arcane power from compact mana crystals (which became a popular product). In Outland, Kael'thas' magisters had refined their usage of mana crystals to the point where they could siphon large amounts of energy in a matter of seconds. They did this by attuning smaller bloodgem crystal shards to larger, fully charged ones.
- The crystals are referred to by many names; if there is an umbrella term for them or one official name for the crystals in general, it's unclear.
- Idle dialogue between Sunreaver Magi implies that the crystals are blue in their natural state; the speaking magus will express gratitude that someone "took the time to apply some proper aesthetics." This is probably a humorous nod to the blood elves' penchant for crimson.
- In Blood of the Highborne, the blood elves in Quel'Thalas suffered from lack of magic so they sucked it from small crystals called mana crystals. At least one crystal that Lor'themar Theron sent through Halduron Brightwing to Liadrin when she was living in the Ghostlands was described as green. Whether it means that it was fel is unclear. However, Rommath wore a green-colored amulet, yet its power was said to be arcane. Those were apparently not the subject of this article.
- In Warcraft III, what looked like mana crystals could be found as props all around Quel'Thalas, possibly being used as mana batteries like the future fel crystals. In Dalaran such crystals were also used by the archmagi raising a defensive shield against the Scourge.
It is possible that the mana crystals are the regular state of the fel crystals (also known as Burning Crystals), which were once used to store demonic energy in the same manner as the mana crystals store the arcane. Both crystals share the same design and textures, though the fel crystals were fel-green instead of crimson. It may be that storing demonic energies in the mana crystals caused their complexion to change thusly. It is also possible that the red crystals were the more demonic, though kept that color in current times for aesthetic reasons.
A cluster of crystals at the Dawnseeker Promontory.
Some blue mana crystals floating in Quel'Thalas.
Blue mana crystals in Warcraft III.
"Power Generator" mana crystal in The Frozen Throne.
"Power Generator" mana crystal in Reforged.
- Bloodcrystal and (blood crystals)