Players who want a low-stress way to play autobattler Dota Underlords without risking their precious rank will soon be able to do that, as it's getting separate casual and ranked modes in the next update. As Valve's blog post puts it, with tongue firmly in cheek, "we've made the ground-breaking design decision to have two ways of playing".
To unlock the ranked mode you'll have to complete at least five games in casual. Daily challenges can still be completed in casual mode, and you can queue up solo or with friends. However, in ranked mode you'll only be able to queue solo, which is bound to be a bummer for some people.
There's also a new rank system coming, one that's designed to be more transparent, and in which "your Rank is now a number you can see that moves up and down in a predictable way. This change is based solely on where you finish in a Ranked match and does not depend on your opponents' Rank."