This at first doesn't sound like a big deal, even sounding beneficial as it means the rate at which you gain EXP will remain constant as you're always fighting against enemies around your level, but monsters gain far more stats from their levels than human units do, as humans are supposed to depend a lot on equipment to buff their stats
When many decks are drawing completely dead against a three-drop, that's a strong incentive to find a way to play it or at least sideboard it, even if your deck suffers quite a bit while the card is in play
Usually, this is an aura or another creature, but the other card types can give menace
and the Through the Ages bonus sheet is chock-full of EDH staples, from Atraxa, Grand Unifier and Ragavan, Nimble Pilferer to Brainstorm and Force of Negation
Bloodline Bidding Tribal decks are the heart and soul of Lorwyn, and Bloodline Bidding is a fantastic one-sided reanimation payoff for this set
Biogenic Ooze is an old combo deck using creature cards in the grave, but now with Trazyn, he can be your commander and instead wants artifacts