The writer got mad when a goblin shoved Astarion off a cliff. It reminded me of when I had Karlach shove a goblin in lava, then a goblin ran up and shoved HER in the lava. I didn’t get mad; I took it as a learning moment: enemies can shove me back, so move away from the lava.
The easiest cheese is to send a rogue in alone to kill it from stealth. The ai isn’t smart enough to find you if you start on the higher ledges. Attack, bonus action hide, move, repeat.
Doing it straight didn’t give me a lot of trouble. Spread out, don’t skimp on spell slots. Spiritual weapon and flaming sphere are pretty good and might distract the owl bear into hitting them instead of you.
Dnd 5e isn’t a very deep game so there aren’t that many options, really .