This thing will basically always give you an immediate impact that is powerful and then if it sticks around the game is well and truly over for your opponent 5/5 worth of stats for 4 mana is a great starting point, and the Gutter-Dweller also happens to be able to grow and draw you cards using the expendable bodies he gives you
Planeswalkers that have no means of protecting themselves are generally too weak for the cube as they are generally quite expensive sorceries
The Four Pillars of Rarity The four standard tiers are not arbitrary
Legality depends on the tournament format -- Zodiac Goat can be legal in some formats and banned or restricted in others
negate the activation, and if you do, destroy that card, then destroy any other cards in the same column the destroyed card was in, that are in the Monster Zones or Spell & Trap Zones
This was the basic composition of every pack released from Shards of Alara until Play boosters were introduced in Murders at Karlov Manor