Relic of Sauron You have to be playing a Grixis commander for Relic of Sauron, which is far more restrictive than most mana rocks
Only 20 copies were ever handed out, meaning this is an incredibly rare prize card
However, there are better cards like Arlinn, the Pack's Hope or Tovolar, Dire Overlord that offer more impactful abilities and synergies with day and night mechanics, making them more viable options for competitive play
So, a card like Green Slime can be a super Naturalize that also invalidates the permanents ETB effect
I think the Arcanine looks pretty cool, but the overall card layout just doesnt do it for me
The Blue and Green Praetors, Jin-Gitaxias and Vorinclex would also have been exciting to see, and would have made a significant in both that individual game of Pack Wars as well as my collection of potential cards for Commander