So I've had an idea for a roguelike deckbuilder for a while that I've decided to start getting to work on now that I feel like I have the capabilities to do so. Now I don't really have a problem with coming up with ideas, most likely the opposite, but I've sort of ran into a separate issue that I'm curious to hear about others process on this.

Balancing.

For myself right now, I've gone ahead and bought a couple of blank whiteboard cards, infinitokens for all my MTG fans out there, for me to start drawing out some of the cards on to play with, as well as a hexagonal playmat that most of the games combat plays on. With this I've more or less consigned myself to playing hours upon hours of my gameplay, which I'm okay with since this is a type of game I'd wish someone else would make so that I could play it, as well as roping in any poor saps to test it out on. But I'm curious, how do most other folks go about balancing games or maybe their process in doing so? Would there maybe be a better way of me going about doing this rather than doing it in a way that feels a little bit brute force?

The way you're doing it is the right way. Until and unless you find a better one (then you can write a book about it).

The more testers you can rope in, the better, because there are different player types.

Some analysis might help you avoid testing (and implementing) pointless or redundant or uninteresting features, reserving your effort for important aspects of the game. For example:

• If different elemental resistances, damage types and the like work the same way you don't need to test each of them and each combination, but only generic cases.
• If combat statistics scale suitably, killing a rat with a dagger might be exactly the same fight (chance of success, duration, etc.) as killing a boar with a sword, just with smaller numbers. Such an equivalence could be a desirable benchmark and a source of useful constraints, or a guide to help you break symmetry with more nuanced rules.
• If poisoned creatures die if they don't take an antidote within X turns, you can determine their fate by simple calculations based on antidote location on the map and best case or worst case movement rates.
• The ordering of events first might be, in some cases, immaterial, making anything that gives “initiative” bonuses not worth using and not worth testing,