With the right combination of cards, you can make it near-impossible to remove Anti-Venom, and thus, near-impossible to deal damage to you
Lots of interaction helps keep opponents off your case while you focus on questing and racking up that game-winning lore
Building a deck around +1/+1 counters, or lifelink, for example, provides you with more mechanical synergy than just jamming all the cool Elves you love into a deck
This limitation was lowered a bit by Heartstone, and basically removed once Training Grounds appeared, which can reduce almost all of the untap cards' ability costs to 1 or 0, if you find a way to tap them for mana, thus allowing such things as infinite 1/1 tokens, infinite mana, or a +infinity power boost to all of your creatures
If you somehow transform Smoldering Werewolf into Erupting Dreadwolf after it has attacked, Erupting Dreadwolf's triggered ability won't trigger that combat