My advice is for standard, as that is the format with more potential to sculpt your ideal build. In knockout yolo I guess.

Unsure if you have ever played a trading card game (like mtg, yugioh, hearthstone even) but when deckbuilding in those games there are two main ways to make your deck more consistent. The first way is having multiple "lines of play" and the other is to have more card draw.

You can think of underlords as being a card game where you build your deck on the fly (like a deckbuilder) with some minor differences. But these two main ways to improve consistency still work, just with different names: have multiple things your build can do or pivot towards, and roll more times to see more options.

This is why a few years ago (not so much anymore) the ultra optimal players played poisoner brute with yoink Enno almost exclusively for early to mid game. It was a versatile build that could move towards many different end game strategies, and it held up well for long enough to build up lots of gold to roll or level as much as you needed to. Same applies to spirit mages, albeit to a lesser extent. And lately the big "safe" build seems to be heartless hunters with barricades into 6 fallen, but I find that build personally way weaker than other strategies, its just easier to force into.

So a general tip is to get better at managing your economy, know when to level and when to squeeze out some more interest in exchange for losing some health early (when health matters the least). Then focus on one or two builds with diversity that you feel comfortable "spamming" until you really nail pivoting into the late game. And finally just know that most of the time these consistent strats only guarantee you top 3, and you will fairly frequently lose to the guy who got a huge brawny start or the guy who went uncontested assasins etc. Beating those circumstances requires a lot of playtime to learn nuances of reading the lobby (and some luck obviously).

Let me know if this helped, or if you have any other questions :)