FanGame talk:Monster hunter: Mark of jiiva/@comment-44547325-20200112211735

Demon-horn diablos replaces black diablos as it is not mating season during the time frame that the game takes place in.

Demon-horn diablos are thought to a random mutation that causes them to have larger, serrated horns and a face that looks like it has a skull pattern on it, this pattern is black. It is also much more aggressive and researchers often compare it to bloodbath diablos in terms of aggressiveness and out right destructive power.