The Plague Tree is the mystical tree and product of The Chant as well as a supernatural Doomsday Weapon featured in the 2015 dark fantasy movie The Last Witch Hunter.
Whenever The Chant is started, a plague tree would sprouted to the ground and grew. While the process and growth is not seen in the film, it is apparent that they grew in extreme speed, as by the time Chloe, Kaulder, and 37th Dolan were heading for the Witch Prison on the same night where the legendary Witch Queen was revived, the tree has already grew and fill the whole church.
A Plague Tree is described as a decayed tree full of branches and roots with enormous size. The largest one of these trees are the one that as enormous as a mountain that can be seen on the vast distance. This particular tree also utilized as the Witch Queen’s lair back during the Black Death, which also gave her and her followers advantages as the whole place also a maze to confuse the intruders.
The fruit-like growth on the tree is not an actual fruit, but rather a hive both to create and incubating larvae of plague fly. Once the chanting nearly in completion, the swarm of full-grown plague flies will be released and wiping out any humans on sight.
Like regular trees, Plague Tree can be destroyed through incineration. But incineration is not enough to kill all flies within since the growth of Plague Tree is controlled by The Chant. So, it means the most effective way in wiping out this supernatural products was by stopping The Chant ritual first, before burned the tree. Although, the tree would immediately become useless has all present casters are dead or stopped the spell completely, with plague flies within died out.