So I'm relatively new to magic and recently went to a local draft. In one of my matches, my opponent played Corpseweft and activated its ability to exile 3 creatures from their graveyard and summoned a 2/2, 4/4, and 6/6 black Zombie Horror creature token. Which means he has 3 zombie horrors summoned all at one time. My first question is that shouldn't it actually just be a single 6/6 black Zombie Horror creature token? I kept reading over the card and didn't think it was played correctly, but they insisted me that's how it works. Again, I'm new so I didn't want to further doubt a player more experienced than me.
I have searched around the internet for discussions on this card but there was little information I found. From the little information I did stumble upon though, it seemed like a back and forth argument in which I wasn't sure which side was right. Could someone please clarify all this?