Carrion Crawler

Domesticated. Has a saddle that says Zyn on it. Handle animal DC 13 to tame it. Can ride it on the ceiling if strapped into the saddle.
Keen Smell. The carrion crawler has advantage on Wisdom (Perception) checks that rely on smell.
Spider Climb. The carrion crawler can climb difficult surfaces, including upside down on ceilings, without needing to make an ability check.