Dabor said:

So there's a mini-quest somewhere in the tutorial that was something like "upgrade 6 life artifacts on a 3 star support hero to level 4 or higher". I used the artefacts on other heroes immediatly after getting them, and from here no matter what I try to do the quest won't progress past 1/6. I put all of the specific 3-star life artefacts on the support hero, re-upgraded them to level 5 - nothing makes it budge past 1/6.

I can't say it's likely I'll be continuing to play your game if it took me just an hour of playing for my ability to follow progress to snap in half as punishment for trying to examine the multitude of options thrown at you, but at least I can mention it so you can fix it for other players.

Bi

 That quest needed new unequipped artifacts before you start. After need to equip one by one.

i hope is help a little. 

That does help me bypass it if I need to, at least, although it's still *very* poor game design to have that hidden extra condition. Having a bunch of existing level 4 artefacts, equipoing them to the 3 star support hero, and then upgrading them all to level 5 absolutely sounds like it should meet the condition. The fact that it doesn't is an unacceptable mistake in a tutorial.