The object is to reduce your opponents health to zero, by breaking through their defenses one way or the other
Ultimately, the five-cost enchantment narrowly wins out over the seven, since it's likely to make it into play far more often
Karn even resulted in the banning of Mycosynth Lattice in Modern since turning everything into artifacts and stopping your opponents artifacts from activating abilities stops them from ever tapping their lands for mana again
TCG' Sets ")
If you pay two mana and discard the card, you can: "Destroy target artifact, enchantment, or nonbasic land an opponent controls
Elspeth, Gideon, and Ajani are good planeswalkers to have among your creature-heavy decks, and good examples are Gideon Jura, Gideon, Ally of Zendikar, Elspeth, Knight-Errant, and Ajani, Adversary of Tyrants