Blood of the Mountain

Many cultures in Colossus have dabbled in Blood. Whether it be magically, alchemically or artistically.
In the nation of Etoria there is a particular type of blood that holds such potent properties that so far they have only found it save to feed to those with a draconic bloodline themselves.
The Spearatus, elite fighting Gnomes of the Tiger Empress, ween their Wyverns on it. It is the first thing they feed on from the egg. Change happens over time with the Wyvernlings, physically as well as intellectually.
No one Wyvern has reacted the same to the ingestion of the blood. All, however, become something else.
The Empress forbid any use of it on any other. It was not the chance of death but the risk of creating something dark and terrible that scared them. The blood came from an entity that only the Spearatus were skilled enough to acquire.
The Mountain range called Tarrasque is said to have veins of blood that run deep within. Those daring or greedy enough to try retrieve it are never seen again.
Rumour has it that the Spearatus are the ones keeping it safe and secret. Others believe it to be too dangerous and none should acquire it.
Having experimented on the Wyverns and seeing the enhancements it gives them led to the Gnomes trying it as fuel for magical means, such as rituals of summoning, planar travel and on the occasion using it as a component in Divination.
It is incredibly rare and therefore sort after by many. A single vial could bring a monarchs ransom. But to survive ingesting it, or fuelling magic with it is a reward on its own.
Know that there is always a cost to Blood magic, and sometimes the price may not be worth it....