[Chris_Byler]

I think the Tengu are intended mainly for Jomon, but the other two eras have them (theoretically) for thematic reasons. They don't play much of a role unless you design your pretender to be able to summon them, and even then, you may have to have your pretender sit around auspexing to get the gem income (unless you conquer an air nation).

If you *do* conquer an air nation, or you find some site-based mage that lets you spam Auspex and get an air income, then you can use them as a sideline, but they don't form a large part of Yomi or Shinuyama strategy IMO.