You will get a lot of these heroes because they’re very easy to obtain. Source of them:
Normal Dungeon, on normal difficulty you’re probably get 1 star heroes drop, but you will get more frequently 2 star heroes drop on hard difficulty.
Social point summon, from my summon experience you get more 2 star heroes than 1 star heroes.
3 star heroes
3 stars are common drop on hard difficulty.
You will need a lot of these heroes, because this is basically a food for 5 star heroes so you can get 6 stars on this game. Best way to get 3 star heroes from:
Available from normal dungeon drop (hard difficulty and above).
Hero Package, always buy the luxury pack to get at least (11x) of 3 stars heroes. Each draw has 90% chance of obtaining 3 star heroes.
Shiny Hero scroll, the chance of obtaining 3 star heroes is about the same as luxury summons (90%).
Secret Dungeons, you probably gonna a mass a lot of 3 star hero pieces, because the difficulty spike from intermediate to advanced secret dungeon. 40 pieces = 3 stars hero.
Evolution from bonus monsters (only power up “+3” bonus monsters, use those “+2” bonus monsters to feed 4 star heroes).
4 star heroes
Best way to obtain 4 stars heroes:
Evolve from 3 stars heroes.
Prime Hero scroll: you get one every time you do the “Luxury Hero” summon 100 times. The chance of obtaining 4 stars hero from the scroll is also 90%, so don’t get your hopes too high to obtain 5 stars hero from this scroll
You can get 4 stars heroes from the hell difficulty mission drops.
Secret dungeons, you need a lot of pieces though (70).
Note: Remember that legendary heroes are start from 4 stars. Even the chance is really small, it’s worth to try to random evo 3 stars heroes to get as many 4 stars heroes as possible.
5 star heroes
At this point, there are no easy way to obtain these heroes, luckily you don’t need to use them to power up any heroes (4 stars already give 25% power up chance for 6 stars heroes, it’s already enough). Best way to obtain 5 stars heroes:
Premium Hero Scroll (5-6 stars heroes summon), you get one every 1000 luxury summons (10 prime hero scrolls). The chance is also 90%, so instant 6 stars hero is only 10%.
Evolve 4 stars heroes
5 stars hero is really rare, I get only 1 5 stars hero after 100 of luxury summons. So, the chance is about 1%.
6 star heroes
There are no easy way to obtain 6 stars heroes. It’s only a matter of hard work on this point.