Realizing that all of its allies are dead, the Owlbear's instincts of survival kick in, and it lets out a bone-shakingly loud screech, before turning tailfeathers and running.

Spoiler
Show
Actions
Standard - Dazing Hoot, centered on H8 VS Fort
Evalie - (1d20+15)[2](17)
Ewin - (1d20+15)[11](26)
Damage
(5d6+8)[4][1][1][4][2](20), and the target is dazed, save ends.

Lucius gets an OA. Ewin's turn, if he would like to pursue through the dense forest.