Hi, welcome.
It is an interesting idea but I could see a few potential problems.
The first one being that I think that Raid functions quite differently from turn based card games. Those lend themselves to turn based play as players build boards and due to (sometimes) intricate board states, players specifically need lots of opportunities for decisions, especially MTG.
I think from a time standpoint it could also be potentially problematic, specifically in very defensive certain matchups. Higher level arena has tons of defensive comps and depending how much time was given to players, getting through all your arena tokens could end up taking entirely too much time.
We also do have the option of controlling our own side of combat manually, or adjusting the AI to act as we wish.