Mana Crystal

This material found deep underground is a rare and captivating phenomenon - a crystalline formation known as the Mana Crystal.  It is said to originate from the compressed essence of Mana Kidney, an organ that warlocks develop to control their mana within their system. These Mana Crystals possess a unique property, allowing them to absorb and contain excess or defective mana much like the kidney it was formed from, transforming it into a concentrated substance of potent potential. Formed over several years, Mana Crystals take shape from the residual energies of Mana Kidneys belonging to various creatures. The larger the creature, the larger the deposit, resulting in crystals of different sizes. As these crystals grow, they manifest intricate patterns and are predominantly charcoal black, with occasional white spots indicating imperfections in their formation. The centre of the deposit, approximately at the origins of the kidney holds the purest mana. Sages have attempted to artificially create mana crystals, resulting in a grey-hued and fragile gem that has side effects on the body if consumed.
When ground into a fine substance, these Crystals take on a mesmerizing appearance - a dark, shimmering blend of black hues. The resulting powder or tincture derived from grinding these crystals becomes a valuable resource. When consumed or used in medicines, it acts as a conduit, drawing in and neutralizing any surges of uncontrolled or unstable mana within the body.  However, it is important to note that using defective crystals, indicated by the presence of white spots or a grey hue, may lead to unforeseen side effects on the body such as forced mutations.
The creation and procurement of Mana Crystals pose challenges due to the scarcity of deposits and the meticulous process of compressing and refining them. Those fortunate enough to possess these crystals hold a valuable resource, sought after by individuals who seek to harness their power or alleviate the inherent risks associated with magic. 
It has remained in use even after the outlawing of magic, providing an option for those that have a Mana Kidney to control their own mana reserves. Luckily enough for these individuals only a small amount of the crystal is needed to support them for a life time, however it still remains pricy and hard to obtain requiring permission from high ranking guilds.

Taste

Bitter

Color

Black