Not only will I draw 5-6 cards, Ill also end up gaining 20+ life
Some cards (mostly creatures) don't have any information at all in this area (not counting italics text, which we'll get to in a moment), which means they don't have any special abilities
If you tap four untapped Persistent Petitioners, it will cause your opponent to mill 12 cards
Overall, Amethyst, Ruby, and Steel are more focused on attacking while Amber, Emerald, and Sapphire are more supportive, but each can be used to make interesting combinations and people can experiment with seeing what strategies work with their personal play style
As you can see with Druids, that mostly meas messing with lands, either playing extra lands (which is pretty great) or turning those lands into creatures as most druids do once they get access to Awaken