Sigh. Big sigh.
You’re right. I’m looking at gowdb.com. It lists his maximum Magic at mythic ascension as 6. 6+3 is 9. That would be 9 damage.
But I’m underplaying the effect of bonuses. I’m getting +10 from kingdoms and +2 from the guild. I could potentially be getting more if I max out my kingdom power, but that puts his magic at 18. 18 + 3 is 21. Something’s still missing, because my Arcanus’s magic is 22. That implies I have an extra 4 Magic coming from somewhere? My guild sentinel can account for 3 of those, but there’s still a mystery +1. Whatever.
Now, to my credit, that’s how all my other numbers was pulled. So I said Mist Stalker did 15 true damage? Mine does 27. So in a relative sense, my comparisons hold. Arcanus does less damage than an equivalently-ascended Mist Stalker, and Mist Stalker does true damage therefore I rate Mist Stalker higher.
I think it balances out but sounds a little nicer with bigger numbers. Arcanus is still a more or less “par” Epic and doesn’t rock the boat. @VenusBlue has a point: if you’re missing the other cards I named, it’s not a bad card. I had to run lots of “bad” cards when I was a newbie.
I wouldn’t invest in ascending it to Mythic with glory right away. Odds are if you need it that badly, within 2-3 weeks you’ll pull something more powerful and replace it.