Speak With Animals 5e Monstrosity
In many ways its the simplest option and hey its magic so no need to worry too much over realism.
Speak with animals 5e monstrosity. Are just not Beasts any. You can safely kill an owlbear from afar with ranged weapons spells or. That granularity is gone in 5E and as stated Unicorns Griffons etc.
Quicklings CR 1 fey Mischief not murder is one of their core characteristics and this alone speaks volumes. So speak with animals wont work. The creature possesses additional hit points equal to your Charisma modifier.
This spell grants the creature you touch the ability to understand any spoken language it hears. Examples include birds with the Giant. No part of this spell requires that the target creature be able to actually speak.
You gain the ability to comprehend and verbally communicate with beasts for the duration. Speak with Animals 5e. I think its fine to explain all this maybe with a nature or arcana check because the characters.
Because owlbear is Large monstrosity not animal. A unicorn is. You can know the information from the beasts about the nearby locations monsters and also about they have perceived in previous days.
Claim a free adventure now to get started. First one is to literally give them a voice and speech for the benefit of the spell. The creature understands one language you speak.