Hi there, welcome to the forum. 

From the champs you listed: Other than the rare champs that are used in fusions (look for the blue swirl symbols) I don't think any of them are worth investing in let alone keeping long term. Warpriest is OK. You could take her to 40 but I wouldn't go farther as you'll eventually be using her to rank up other champions.

Elhain on the other hand as your starter and campaign farmer is worthy of taking up to 6 stars as soon as possible so she can be most effective.

Hi and thank you! I appreciate the feedback. I'll work on getting her up to a 6 ASAP. I'll sacrifice Dervish. I'm tired of her dying all the time lol. 

generally speaking, you wanna use commons and uncommons for your "chickens" - rank sacrifices

Hang onto your rares for now. you'll outgrow them eventually, but by  the time you do you'll have a much better idea of who's worth building and who's never gonna be anything but food

Armigar is an uncommon champ who is incredibly useful in several places. its worth keeping at least one of him to take to level 60, eventually, just not high priority for where you are right now

Would definitely recommend you watch the HellHades FTP (Free To Play) videos on YouTube - loads of hints and tips in there for upgrading your champions to progress your account.

I upgrade then sacrifice greens for the most part, sometimes blues after I've filled all my faction guardian slots for that particular faction. https://routerlogin.uno/