Elves decks leverage Gaea's Cradle well, but any deck capable of flooding the battlefield with small creatures utilizes this great green land to excellent results
This isnt even considering the extra combat damage youll get to apply with two extra disposable attackers a turn

Facilier, Fortune Teller Super Rare 80 Enchantress, Unexpected Judge Common 81 Flynn Rider, Confident Vagabond Common 82 Flynn Rider, His Own Biggest Fan Rare 83 Gaston, Scheming Suitor Common 84 Little John, Loyal Friend Rare 85 Lucifer, Cunning Cat Rare 86 Pain, Underworld Imp Uncommon 87 Panic, Underworld Imp Common 88 Pete, Bad Guy Rare 89 Prince John, Greediest of All Rare 90 Queen of Hearts, Quick-Tempered Common 91 Ratigan, Criminal Mastermind Common 92 Ray, Easygoing Firefly Common 93 The Queen, Disguised Peddler Super Rare 94 Tiana, True Princess Uncommon 95 Virana, Fang Chief Common 96 Bibbidi Bobbidi Boo Rare 97 Bounce Uncommon 98 Hypnotize Common 99 Improvise Common 100 Pack Antics Rare 101 Ring the Bell Uncommon 102 Ratigans Marvelous Trap Rare 103 Baloo, Fun-Loving Bear Common 104 Boun, Precarious Entrepreneru Common 105 Card Soldiers, Full Deck Uncommon 106 Donald Duck, Not Again

Commander's Sphere is also widely popular for similar reasons: You ramp and fix mana with this rock, and draw a card when needed (for 0 mana, even if tapped out!)
Several other cards allow for extra draw or the return of cards to the hand, keeping an Amber/Amethyst player well-stocked and ready to keep the table full
This keeps the board clear while you prepare to steal the most important threats