If you have three or more creatures, things get out of hand, fast
Any ability that triggers whenever you draw a card, for example, will trigger
In a 60-card deck drawing 7: with 4 copies you have a 39.9% chance of seeing one in your opener
Wizards has defended the incomplete reminder text by pointing out that it's not the first keyword that you have to read the rules to fully understand, and that casual players will assume it works because they assume everything works, while experienced players are all tapped into the data stream and will have heard the clarification before the Prerelease
2 Nicol Bolas, Dragon-God Dragon-God comes in as the lowest costing Nicol Bolas planeswalker, only costing one blue, three black, and one red
Garruk, Unleasheds +1 loyalty ability gives a creature +3/+3 and trample, which forces your opponent to start using unwanted blockers or removal spells early