Endowments are special powers that allow Heroes to do things simply because of who they are; rather than purchasing them as part of a large menu of possible powers (which is how Blessings work), they are inborn skills and qualities that relate to the Hero and the areas in which they are most famous and skilled. Each Hero has three of the possible seven Endowments, giving them a selection of heroic capabilities beyond just their rolls and the powers they choose to invest in. And that number seven does indeed have to do with the seven Aspects - each Hero has the Endowments attached to their highest three Aspects, so that Heroes who take on, for example, a great deal of the Aspect of the Trickster also have access to the unique Endowment that all Tricksters often display.
So, these seven Endowments... what are they and why are they awesome and essential for all Heroes?
- The Creator Endowment draws upon a Creator's innate powers to make and sustain, giving them an Empowerment to use Blessings far more effectively than anyone else. They can increase the effects of specific Creator Blessings to heights that mere dabblers could not as they pull from reservoirs of sustaining energy within themselves.
- The Hunter Endowment is their incredible Persistence in the face of hardship, which allows them to carry on with their hunts and tasks long after they should have given up. All Heroes can keep going for longer than they should be able to by purchasing Mettle to temporarily stave off the effects fo their exhaustion, of course, but only Hunters have the Persistence to simply decide not to be exhausted at all.
- The Leader Endowment represents their Sway over the people and organizations around them, which naturally recognize their leadership skills. They can leverage that Sway to call upon people (sometimes even people they don't know) to perform tasks for them, go on errands, get them resources, or whatever else they need. Of course, those people don't always survive or have the ability to help again after the Leader's leveraged them... but all leaders have to manage their human resources at some point.
- The Lover Endowment allows them to count on occasional help and affection from Faithful Allies, who are friends, lovers, family members, or any other people who have a strong and abiding love for the Hero. Faithful Allies turn up seemingly at random during the course of the Hero's adventures to perform grand gestures of their love, giving the Hero gifts, resources, or personal aid when they might need it most. Of course, occasionally they also need help or rescue from their Hero if they try to do so in a particularly dangerous situation... but these are the perils of being so lovable that people literally run into danger to make sure you know they adore you.
- The Sage Endowment represents their incredible powers of Focus, which allow them to tap into otherwise inaccessible wells of resources and ability. They are capable of using their other Endowments more often than they should be able to, since they can channel their inner energies into powering them more efficiently than anyone else.
- The Trickster Endowment is all about performing Gambits - ridiculous, ill-advised, and often only partially successful secret plans and gambles designed to allow the Trickster to get out of sticky situations or snatch triumph from the jaws of defeat with extremely sketchy methods. Gambits are always a risk, sometimes allowing the Hero to succeed against all odds and show off their incredible cleverness, but also sometimes resulting in ignominious failure and accidental misfires as the plan that seemed so foolproof a minute ago turned out to in fact be perilous and severely badly timed.
- The Warrior is of course already strong and capable of feats of physical prowess, and so is anyone else who has Brawn... but only the Warrior can decide to put themself into Overextension, pushing their body beyond the normal limits of pain and ability to do ever more unreasonable feats. Overextended Warriors can lift heavier things and destroy more solid structures than anyone else, even those who have the most Brawn possible.
As you can see, three Endowments (Leader, Lover, and Trickster) are what we think of as "story powers", that have a large narrative effect on the game and are of varying levels of effectiveness depending on what's happening, and three Endowments (Creator, Hunter, and Warrior) are what we think of as "personal powers", allowing their users to boost their own capabilities. Sage is the odd one out, enabling either kind to be used more often.
As for Reserves, they're the resources that Heroes spend in order to activate their Endowments; Heroes have only a very small pool of them, but when they're used, big things happen in the story. Heroes will get more Reserves as they become more powerful and grow toward godhood, but they'll always have few enough that rationing when and how to use them is important.
We're big fans of Endowments as powers that everyone gets to support their character type, regardless of what else they choose to do. If you want to be strongly Warriorly or epically Loverful, you'll have the ability to do big things like Warriors and Lovers of old, regardless of how you specialize, because that's who you are and how you shape the story around you.