“Discard this card to reduce the difficulty of *ANY* check against a card with the Human trait by 4”

 

Assuming that “any” means any, you should be able to play this against allies cards (so long as it reads “Human” on it), right?

 

That being said, either the card is bugged or needs to be reworded.

 

P.S. played Song of Hawkmoon against a Blacksmith ally card and still had to roll a 4 to get him

Also doesn't seem to apply when played against other character's encounters, even though the card is highlighted, can be selected/discarded, etc.