Lectoblixes are a species of blix, they age quickly, and survive by draining the youth of others. In Secrets of the Dragon Sanctuary, Torina reveals herself to Kendra as a Lectoblix. Held captive with Kendra are several of Torina's elderly' victims. Out of 'kindness' she allowed them some years left to live, but others she absorbed all youth out until they perished from old age.
However, they have one weakness. When a Lectoblix tries to drain a unicorn, they perish as the amount of purity inside a unicorn overwhelms them as demonstrated when Torina attempted to drain Bracken.