Color : Each element is very strongly associated with a Magic color (water with blue, earth with green, fire with red, and air with white)

Example Lists Mono Green Creature Based 24 Spells Llanowar Elves Fyndhorn Elves Elvish Mystic Joraga Treespeaker Noble Hierarch Skullclamp Rofellos, Llanowar Emissary Lotus Cobra Devoted Druid Explore Sylvan Advocate Satyr Wayfinder Tireless Tracker Rishkar, Peema Renegade Yavimaya Dryad Oracle of Mul Daya Garruk Wildspeaker Nissa, Worldwaker Verdurous Gearhulk Primeval Titan Walking Ballista Hornet Queen Crafterhoof Behemoth Decimator of Provinces 16 Lands Gaea's Cradle Treetop Village Rishadan Port 13 Forests Gr Ramp 23 Spells Search for Tomorrow Birds of Paradise Oath of Nissa Joraga Tree Speaker Arbor Elf Explore Sakura Tribe Elder Nature's Lore Sylvan Library Sylvan Caryatid Yavimaya Dryad Nissa, the Vastwood Seer Courser of Kruphix Den Protector Oracle of Mul Daya Polukranos, World Eater Garruk Relentless Nissa, Vital Force Primeval Titan Dragonlord Atarka Avenger of Zendikar Ugin, the Spirit Dragon 17 Lands Nykthos, Shrine to Nyx Myriad Landscape Kessig Wolf Run Tiaga Wooded Foothills Stomping Ground Raging Ravine Temple of Abandon 9 Forests These are just two fairly standard example lists

Are they worth spending your hard earned cash, or precious Wild Cards on these cards
What did I miss and why?
This card is a great example of how trainers can bring so much to a card and N reigns king of them all as one of the best in the TCG, no matter the card
This one costs five mana, and reads, Whenever enchanted player casts an instant or sorcery spell, each other player may copy that spell and may choose new targets for the copy they control. Its great for playing against control players, because then everyone can choose to counter their nonsense