And probably it's the same reason why people doesn't use him, since that it is quite predictable that you are using a D-Hero/ Masked Hero deck when you use him as a character. Probably because of dark city skill.
Very rare I encounter people using Aster with a non-D-Hero deck.
If you use destiny calling, all you can do is hope your opponent has already used or won't get some spell removal. With balance being nerfed, there aren't really any good skills for him, so unless someone really likes him, they won't use him. At least I really don't have to worry about mirror matches.
I used balance for my amazoness deck with 10 monsters, 9 traps, and 1 spell. Always got the perfect starting hand. But now it sucks. I am just using draw sense dark in the hopes that I can at least gain some advantage by getting vision hero witch raider out faster if I brick with a hand full of traps.
I am not sure. It is easier to find them at all levels when they are at the gate. All you can do is keep completing the stage missions and checking. When you do duel him at lv. 30, get ready for his clock tower prison. It can be a headache.