Current questions and answers regarding the map editor.

You select the type of reward - artifact, and I highlighted the field where you choose it in the screenshot.

Added after 5 hours 23 minutes
Is there a way to completely disable the AI companion so that it does nothing?

You didn't quite understand me. I want the quests to require bringing an artifact, but the reward should be an army (for example, bring a crown, and you get archers). In the "type" field in the "award" tab, I set it to AWARD_CREATURE. I probably need to specify something in the "aeard" tab, but I don't know where (