I don't know if I agree it's a card you NEED, but if your Commander deck is specializing around Goblins, this card is something you are going to need and want
One other note: The big spells theme is rather well-supported, so dont think you always have to be UR to take advantage of it
Blue and white center on going over your opponents heads with flying creatures, while mono green (my favorite and the best way to play) favors big, stompy creatures that run over your opponents defenses
The dark side of Magic isnt going away
Depending on the creature type, you could run at least 30 to 40 or more creatures in the build
Sin, Spira's Punishment Rarity: Rare TYPE: Legendary Creature SUBTYPE: Leviathan Avatar CMC: 7 Mana cost: USD: $1.68 EUR: 1.65 TIX: 0.02 EDHREC RANK: 9638 (7/7) Flying Whenever Sin enters or attacks, exile a permanent card from your graveyard at random, then create a tapped token that's a copy of that card