This is only good advice in cube play, you will note modern decks do not take this advice and this is because in cube you very rarely face mirrors due to the card pool being what it is
Ulvenwald Hydra is great in any deck relying on Land totals and searching for any land, because its Power and Toughness are tied to how many Lands you control and it Rampant Growths when it enters
Two separate draw/discard instances gives you plenty of room to pitch a Dredge card and use its ability, and it provides pressure on the board to boot
Simple packing them is often not enough
Whenever chaos ensues, create two 2/2 black Alien Angel artifact creature tokens with first strike, vigilance, and "Whenever an opponent casts a creature spell, this permanent isn't a creature until end of turn." As the triggered ability of the Alien Angel token resolves, it continues to be an artifact but will stop being both an Alien and an Angel until it becomes a creature again
The box set releases in October 2026