Completed both campaigns in all difficulties with budget decks, yes it's more than doable, by completing that (FREE content) you get a lot of in game currency such as gold to buy more packs, essence to craft more cards etc as well unlocking new champions. The game will have a lot more to offer once new content is released and new features are implemented, as for now it's solid and I like the path where it's going. If you're struggling, join Runestrike's discord.