I don’t have heroes quite at 10*, so I don’t know if it’s a daily thing you get or what. I’d like to know cause I have at least one hero at 8*
You get 50 heronium for every dubbel frag you own.
You can exchange that for gear or frags, 30 frags cost 1500 heronium, 20 cost 1000 and 10 cost 500, so it’s a trade 1 to 1
The max you can get of each type is 60 a day, it resets at the same time the rest of the stores do
You can also buy specific hero frags but those are really expensive, same as typeles frags
I have one 10*: Dogface. A good one to have at 10* since you can farm him from the Gauntlet store. As Kraterios said when you receive a framgmet of a hero you have at 10* you instead get a slab of heronium to spend in the Heronium store.
While I most often spend my Gauntlet gems on golden knives and throwing stars it’s nice to be able to buy Dogface / Heronium if I stress out and need a couples of dozens of fragments in a chosen color from the Heronium store.