Trombe

Trombe (トロンべ, toronbe) is a feyplant that grows very quickly and absorbs the mana in the ground and surrounding plant life to help it grow faster. It could potentially drain enough mana to turn a forest into a wasteland.

When a trombe fruit becomes active, it pops into a number of small seeds that spread out over a small area. The seeds immediately start absorbing mana, making the sprouts grow rapidly and causing the mana drained ground to turn gray.

The sprouts act like tentacles which instinctively seek out and coil around other sources of mana, such as plants and animals. The sprouts and roots will quickly drain the mana of anything they touch, helping the Trombe to grow.

The greater the mana the trombe is exposed to, the faster and larger it will grow. For example, due to Myne compressing her mana for years, the mana quantity in her blood is highly potent, and even a single drop is enough to cause a Trombe to grow at a much faster rate.

If a trombe fruit is not exposed to large amounts of mana, the seeds burry deep undergound and stay dormant for quite some time while they slowly gather up the mana necessary to grow, which makes it practically impossible to get rid of or anticipate until the young plants break the surface.

While it is still a small sprout, it can easily be cut down by a few children with knives, though it quickly grows to a thickness and hardness that require strong adults to cut down.

If it isn't cut down within minutes of sprouting or if they are fed by an unusually strong source of mana, they become too resilient to regular steel for commoners to be able to deal with them. In such cases the Knight's Order is mobilized to destroy the trombe. The Knights use the blessing of the God of Darkness to enhance their weapons with mana-draining properties, allowing them to deplete the mana that keeps the Trombe alive, causing it to wither upon being struck.

Trombe and Taue are feyplants of the same species, but different genders. The seemingly harmless Taue trees are the females, producing the fruits, while the aggressive and dangerous Trombe are their male counterpart, which fling their spores far and wide while flailing around.

Spoiler from Part 4 Volume 7 The only place in the country of Yurgenschmidt where trombes are known to grow is the Duchy of Ehrenfest.