Hey jumping into this thread here. What about factoring food cost which I am ALWAYS short of? It costs 2-3X more food to level mid level hero’s with 1* vs. 2*. For example for my 4* LVL 25 hero its about 125,000 food to go up 10 levels with 1* or about 50,000 food with 2*. It’s only at low levels of 3* it is somewhat close. I only level generally with 2* with my 4* and 5* hero’s since the food costs are so high. And I never have enough food so this stretches my food dollar a LOT.
If you are at risk of not maxing your special skill, I agree only using 1* since they level so inefficiently your hero, you get lots of tries to increase your special skill.
On the probability side, over the long run, the probability of doing each card on its own (eg. 2*, 4% chance) vs. doing 10 at once (40% chance) is the same. BUT the food cost is more expensive doing it one at a time as each level, the food cost increases.
I’m still newish to the game (LVL 11 SH) so still figuring things out