Left click
Horn attack
Left click performs the main horn attack. It punishes anything entering the frontal arc, finishes a stopped target, or takes initiative after an enemy gives a bad angle. Diablo wins when it forces opponents through the space in front of its head.
Sprint + left click
Charge / shove
While sprinting, left click becomes a short charge that can shove, stun, or knock down depending on target weight. It is powerful, but not an endless chase tool: charge to create separation or punish a commit, then return to formation instead of running too far.
Hold right click
Brace / frontal guard
Holding right click lowers the head and puts Diablo into a defensive stance. It moves more slowly and cannot use a normal headbutt while braced, but it takes frontal pressure much better, especially to the head. This is the button that turns a duel into a patience test: show the horns, let the enemy commit, then answer.
Sparring: spacebar + direction
Horn sparring
Against another ceratopsian, horns can lock together. The fight becomes more technical: push, resist, choose the right movement, and keep enough stamina to break the lock. To disengage, use spacebar with a movement direction.