Consider commanders like Arna Kennerud, The Mindskinner, and Talrand for something creative and not too broken
The destruction aspect is an optional effect that happens at the end of the card effect
If one deck is fast and aggressive, and the other is a slow control deck, Winter Orb can be devastating
+2/+2 is a nice bump, and the Convoke ability should let Goblins, Elves, Merfolk, etc
Every pack of Double Masters has two raresand when you booster draft, you can pick them both
Unfortunately there's no other conditions dictating what opponents do with their new 4/4, so if you don't have a plan to really make use of the fungus tokens, this can be quite a negative card