Giant Owl

A giant owl working with the party is a Celestial scout and messenger. She speaks Celestial and understands Common, Elvish, and Sylvan. With 60 feet of fly speed, Perception +6, Stealth +6, and Darkvision 120 feet, she does reconnaissance without rolling. Send her ahead of the party. She circles a camp, a tower, or a valley, reports what she sees with no dice involved, and comes back.

Use her to collapse overland travel into narrative beats. The party camps on a hilltop and needs to know if the bandits at the base are awake. Send the owl to watch their campfire. She returns in five minutes with the answer. The party avoids a road because scouts report trouble. Send the owl to confirm whether the road is actually blocked. She keeps travel days from becoming spreadsheets.

Tactically, the owl has no listed attack action. She has Talons (1d10+2 slashing) and Spellcasting with Detect Evil and Good, Detect Magic at will and Clairvoyance once per day. In a fight, she stays airborne, uses Flyby to never trigger opportunity attacks, and stays at 60 feet where the party's melee can't reach. She can contribute to intelligence gathering but not damage dealing. If combat forces her to fight, she survives a few hits and then retreats.

The owl belongs to someone. A druid patron, a high elf scout, a forest deity's emissary. Give her a name, and when the party returns her safely after a task, the owner owes them a favor. When she falls on a scouting mission they sent her on, that NPC grieves, and the party feels the weight of it.

A hostile giant owl is an unusual framing and best played as bound against her nature. A hag has enslaved her with magic. A duergar has captured her and uses her to track the party's movements. A corrupted druid has twisted her loyalty. The owl is unwilling, and that unwillingness is the emotional core of the encounter.

Run her as a harasser and spy, not a combatant. She circles at 60 feet of altitude, well outside torchlight and melee range. Her Perception +6 and Darkvision 120 feet mean she sees the party clearly. Each night, she hoots three times and flits away, relaying the party's location to whoever controls her. The party hears the calls but can't reach the caller. The unease is the real threat.

If the party forces combat, the owl has 19 HP and AC 12. Her Talons do 1d10+2 slashing. She uses Flyby to strike and escape without taking opportunity attacks. But she's a scout, not a fighter. Once she's badly hurt, she flies into thick cloud or fog and disappears. Her death should matter. Her captor arrives later, angry and grieving, and that anger becomes the next hook.

The owl's spellcasting (Detect Evil and Good, Detect Magic, Clairvoyance) means she could scout the party's intentions or lair. Use that possibility to unsettle the players. Have the owl clearly watching them during a long rest.