Yet when I bring up the page to sell characters, I only see an option to gain Iso-8. Can someone explain how you get HP for heroes sold?
Sentry and Hood have (had?) increased prices that included HP after they made gameplay changes to both. Similar happened with Daken and Hawkeye changes. I don’t know that Daredevil or Loki had the same happen for them.
It used to be that 3* characters would sell for HP, but those are days of yore now.
As a general rule of thumb, when characters are re-worked, they offer to give bonus ISO-8, as well as a scaling amount of Hero Points, for a period of time.
Right now you can sell Sentry and The Hood in this manner.
I have both of these heroes and neither shows any hero points as a return value.
Sentry is only one cover ( 
), but for Hood I have 3 
1 
and 4
but also shows no hero points.
The HP doesn’t show up until around level 50-55,IIRC. It’s also possible those sale prices have expired.
Prices are still live but it’s entirely dependent on the level of the character.
You need to have at least 3 covers and to put iso to be at current max level.