The Path of the Totem Warrior barbarian (PHB, p. 50) gets the Aspect of the Beast feature at 6th level, with a number of different totem options with different benefits. The Eagle totem description states:
You gain the eyesight of an eagle. You can see up to 1 mile away with no difficulty, able to discern even fine details as though looking at something no more than 100 feet away from you. Additionally, dim light doesn't impose disadvantage on your Wisdom (Perception) checks.
Perhaps I'm being facetious, but the wording on this seems to imply that you can see 1 mile away no matter what. Through trees, dirt, rock, magic fog clouds, magical darkness, etc. It doesn't say you need line of sight or that magical effects block it still. It says "no difficulty".
How would a DM interpret that if a player challenged him on this wording RAW?
Best Answer
Eagles can't do that.
It says very clearly "you gain the eyesight of an eagle." Live by exact words, die by exact words.
This is one of those "there ain't no rule that says fire is hot" situations. The rules are meant to be interpreted by someone with at least a little bit of life experience, not by RuleBot 9000.