xy ancient origins booster box 4 Pokemon Packs featuring the Ancient Origins set Ancient Origins Elite Trainer Box

Mark Rosewater has gone into elaborate detail on double-faced cards on his Drive to Work podcast - I would recommend checking this one out for the history of the mechanic

Salamangreat Violet Chimera X FIRE Level 8 [ CyberseFusionEffect ] ATK 2800 DEF 2000 1 "Salamangreat" monster + 1 Link Monster If this card is Fusion Summoned: You can make this card gain ATK equal to half the combined original ATK of the materials used to Summon it, until the end of this turn

Mareep Art Rare Promo can only be obtained from this limited-time event, which means all the TCG Pocket players must participate to get their hands on this rare card

The very first pack I opened had a Blastoise holo