For me - when i was first exploring the swamp and had encountered a few abominations. I would just try to retreat and hit with fire arrows. I was walking backwards towards a Black Forest outpost i had near the swamps shooting at an abomination and turned around and right behind me was a Troll. Did a few dodge rolls to avoid any damage then the Troll and Abomination started fighting. I just kind of stood on the side and watched them fight. It was pretty amazing and unexpected, hadn't looked up much about their behaviors before then. But i definitely learned then to use that tactic more in other biomes.