this game works a bit differently than other android action-RPGs, let me explain why I disagree.
Potions are meant to be emergency lifesavers, they are very expensive, because they're not supposed to be used massively. Getting to the bottom of dungeons should be a matter of optimizing skill usage and getting as little damage as you can.
Example, if as a rogue you use Stealth/Stab on every goblin in the mine, they'll barely hit you. Similar with Whirlwind. Of course if 3 goblins come at you at the same time, you will get hurt, but you have to avoid that, normally enemies can be fought one on one. If you make a mistake and run into 3 zombies, it is time to do some special tactics. for instance, whirlwind, then run around avoiding them until whirlwind is active again. If you are a rogue, run around and lay traps, when Stab becomes usable, stop, stab, and then keep running. If you were close to the deep rooms with chests, spending a potion may be worth it.
If you just jump into enemies and try to automatically defeat them, yeah, you'll just die. And I personally like that. In other games, it's just move to enemy, taptaptaptaptap, nothing interesting. Here you need to dance around, use skills, and know when to run away.
We all got slaughtered in the goblin mines a few times, but with time and a little skill, this game can be beaten, and I am not one of those mega-skilled action game players, my reflexes suck, but eventually I learned how to play each class. It is what makes it fun, at least for me