Rise of the Floodborn added a unique card strategy with bouncing Merlins different shapeshifted forms back from your hand (especially Merlin: Goat), gaining their powerful played abilities over and over again
The standard Two-Diamond Misty currently has a 1.714% pull rate, or " Offering Rate " as it's called in the game, when trying to get it from packs

Sort Rarity Card Type Ampharos #1Holo Rare $40.07 Blastoise #2Holo Rare $93.08 Charizard #3Holo Rare $137.03 Entei #4Holo Rare $39.75 Flygon #5Holo Rare $14.87 Gallade #6Holo Rare $12.60 Gardevoir #7Holo Rare $60.09 Gastrodon East Sea #8Holo Rare $13.73 Gastrodon West Sea #9Holo Rare $10.81 Ho-Oh #10Holo Rare $44.26 Jumpluff #11Holo Rare $11.02 Lickilicky #12Holo Rare $16.26 Ludicolo #13Holo Rare $8.52 Lugia #14Holo Rare $117.95 Mew #15Holo Rare $182.59 Raikou #16Holo Rare $23.55 Roserade #17Holo Rare $5.64 Salamence #18Holo Rare $36.96 Suicune #19Holo Rare $41.20 Venusaur #20Holo Rare $45.64 Absol #21Rare $9.21 Arcanine #22Rare $6.24 Banette #23Rare $1.89 Dugtrio #24Rare $0.89 Electivire #25Rare $1.56 Electrode #26Rare $0.43 Furret #27Rare $3.01 Golduck #28Rare $0.92 Golem #29Rare $1.98 Jynx #30Rare $0.85 Magmortar #31Rare $1.04 Minun #32Rare $3.43 Mothim #33Rare $1.19 Nidoking #34Rare $3.92 Pidgeot #35Rare $2.74 Plusle #36Rare $3.67 Sharpedo #37Rare $1.56 Sunflora #38Rare $1.01 Unown [S] #39Rare $3.25 Weavile #40Rare $1.35 Wormadam Plant Cloak #41Rare $0.91 Wormadam Sandy Cloak #42Rare $0.75 Wormadam Trash Cloak #43Rare $0.85 Xatu #44Rare $1.13 Breloom #45Uncommon $0.98 Charmeleon #46Uncommon $1.81 Cloyster #47Uncommon $0.66 Donphan #48Uncommon $0.30 Farfetch'd #49Uncommon $0.65 Flaaffy #50Uncommon $1.10 Ivysaur #51Uncommon $1.78 Kecleon #52Uncommon $0.64 Kirlia #53Uncommon $1.73 Lombre #54Uncommon $0.42 Miltank #55Uncommon $1.05 Muk #56Uncommon $0.62 Nidorino #57Uncommon $0.37 Pidgeotto #58Uncommon $1.10 Pinsir #59Uncommon $0.41 Quagsire #60Uncommon $2.64 Mew #15Holo Rare $182.59 Charizard #3Holo Rare $137.03 Lugia #14Holo Rare $117.95 Gardevoir LV.X #131Ultra Rare $113.49 Blastoise #2Holo Rare $93.08 Gardevoir #7Holo Rare $60.09 Venusaur #20Holo Rare $45.64 Ho-Oh #10Holo Rare $44.26 Honchkrow LV.X #132Ultra Rare $43.96 Suicune #19Holo Rare $41.20

However, after Prismatic Evolutions, this stunning, once valuable card was made significantly less desirable, dropping its price by over $200
It has been sold in 14 languages, and has been played in 89 countries or regions
The promotion will be active from October 1, 2017 through October 14, 2017, so you have only two weeks to take advantage