For the cost of one mana of each color save for black, when this 4/4 elemental enters the battlefield, its controller draws a card
Un-Set cards get to cheat at card design a bit, so it's not really fair to compare them directly to normal black-bordered cards, but for completionist's sake the two biggest creatures in Magic are technically Infinity Elemental with literal infinite power, and B
This isn't even the worst with Sneak Attack and other one shot things as a 12 point life swing is meaningful
Korvold, Gleeful Glutton costs three more mana than his previous incarnation, though the cost is reduced for each permanent card types you sacrifice before you cast him
The player whose turn it is will put all of their triggered abilities on the stack in any order, then each other player in turn order will do the same
Legality depends on the tournament format -- Heavy Fog can be legal in some formats and banned or restricted in others