cards you have in play is equal to or less than your opponents Don
In general, follow-up sets in Magic can be a little more experimental, as players now have had some time to get the grasp with the foundations, and EMN really delivers on the new and weird front
Knuckles the Echidna Double strike, trample, and haste make Knuckles the Echidna a powerhouse that turns every combat into a burst of damage
Abandoned Air Temple The mana costs are intense in the early turns, so white decks often have plenty of Plains as it is
In addition to that, it becomes extraordinarily good if your deck is filled with mostly only outlaws or non-outlaws, because in that scenario you can use this card to deal damage to multiple opposing creatures while not affecting your own
You can spend one Black mana for two life lost, two cards drawn, and you kill creatures while you do so - so he's basically a stronger effect for most Black decks at the kitchen table as he interacts with your foes' stuff and works well with any life loss effect out there