Tzaraath

Wandering beneath the trees of Bisaya there are a great many demons, things so horrid that men can barely stand to look upon them, but few can claim to have killed so many, or so thoroughly as the Tzaraath. It is a predator that knows no match, hunting alone through forests that have known an unending night for generations.

It stood at least 3 men tall, this thing, and it reeked of a week-old battlefield, that horrid mixture of burnt and rotten flesh, offal, and hatred. That's all I noticed before it set into us, at which point those of us that weren't running set too it with our axes and spears, only to find that its flesh, where it wasn't half rotted, was as hard as stone. It lashed out about itself, with teeth and claws and spikes that protruded from it's sides and back, like some deranged bear. I was lucky and got hit with the back of one of it's hands, and was flung at least 20 paces. That's all that I remember, sir.
Transcript from one of the survivors of the 31st Imperial Division sent to investigate the interior of Bisaya

The island has a peculiarity about it that leads many men to believe that the island itself is alive, and that it views them as a disease upon their surface. Whether or not this is true, the Tzaraath would seem to support this view. It is one of those things that, without having any purpose to exist, and no means to have even come into existence, do.

It hunts beneath the trees, with an uncanny intelligence born as much from years of being hunted as from being the hunter. During the day it sleeps, hanging from the tree branches like a sloth, wakened only by excessive noise, and at night it wakes to hunt the woods. It hunts hunters, the massive cannibal apes and the large cats and men have all fallen prey to its depredations.

Jungle Lynx

One of the smaller hunters on an island that is known for its many ways to die, the Jungle Lynx is none the less one of the most effective killers of men. This isn't because of some supernatural strength, or uncanny intelligence, but because of its pack-nature and their hit and run tactics.

The lynx is small, usually only a foot and a half long without its tail, and dun colored with black stripes going vertically through its body. And an individual lynx is rather weak, unable to defend itself besides by running away.

In spite of this, they are still to be feared. They'll often attack in groups of 7 to 12, jumping out of the trees and slashing at their victim's face and throat, only to jump off again as it begins to defend itself, but as soon as it begins defending its face they'll attack it's hamstrings and back, or its stomach. The beast's inability to defend itself is what allows these things to take down things 5 or 10 times their size, and a solitary human has almost no chance of survival against a determined pack of these.