Trombe

A Trombe is a magical tree 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.

Growth
When a Trombe seed 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 Main 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.

Countermeasures
While it is still a small sprout, it can easily be cut down by a few people with knives, but if it grows larger, it requires members of the Knight Order to ride into battle to destroy it. 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.