How to get All Grown Up achievement?

[Babacan Arda]

No matter how hard I try I cannot bloodwarp single hatchling into a seraph. Game literaly choosing bloodwarping 20 unit of low level melee fighters than one hatchling. Even in huge fights where I get 60k exp I only leave hatclings in the army with best tier units and after fight I dont get any bloodwarping at all. What am I missing?

[Redgomor]

Had the same problem, too. I don't think you can bloodwarp them, if you have the Skill on Level 1, I think it needs at least level 3. And it would be better of course to have them the only upgradeable unit in your roster.

[Tappin]

I just got this with level 1 Bloodwarping, so it's possible. I took a small group of them and hundreds of other things that couldn't be upgraded. I still didn't get an upgrade until after about 10 fights. It might have to do with what else dies during the fight, but having no other choices for upgrades helped.