Though personally, I thought it would be awesome to play a Lythari elf (see the "Rare Elf Subraces" sidebar on SCAG, p. 106) Way of Shadow monk who relies on her smell to scout ahead, I realized that this isn't the only time that a player character might be faced with "Keen Hearing and Smell", as they might:
- Be a druid who wildshapes into a canine
- Be a werewolf
- Use beast sense with their wolf familiar
- Use a Mask of the Wolf
In either case, the wolf's trait states:
Keen Hearing and Smell. The wolf has advantage on Wisdom (Perception) checks that rely on hearing or smell.
However, I'm not quite sure how that works or what range that would work for. Doing a bit of research, I discovered that a wolf, in best conditions, can smell prey up to 1.75 miles away (i.e. 9240 feet), and can rely on their second-best sense, the sense of hearing, as far as 6 miles away in the forest or 10 miles in the open.
Having a dog, I also noticed that their sense of smell seems to work something like blindsight in-game, with the exception that they can follow a scent's trail as if following a ball of yarn that was unraveling.
Wanting more concrete ideas from in-game examples, I discovered the spells Locate Animals or Plants, which has a range of 5 miles, as well as Locate Creature and Locate Object that both have a 1000-foot radius and have this trail sense as well.
Then again, it most likely is the case that I'm reading way to deep into the rules and/or missing a clearer ruling on this found somewhere in a book I haven't read, so I thought I'd ask the community:
How does the mechanic of Keen Hearing and Smell work, and can I use it to hunt/scout like the wolf I am supposed to track?