Mana cost
By the numbersMarket analysis The clear chase of Prismatic Evolutions
Other options may not exactly combo with themselves, but the other combo pieces needed are so generic that it might as well be a 1-card combo
This set introduces a new mechanic called Ultra Beasts, while also introducing new GX cards and many new themes, such as Alolan forms of older generation Pokmon

As it stands, the prices are as follows: Secret Lair x Monster Hunter: The Hunt Blind Obedience - around $3 Snap - around $2.50 Village Rites - around $0.25 Mizzium Mortars - around $0.45 Tooth and Nail - around $2 Total value: $8.20 Secret Lair x Monster Hunter: The Hunters Grand Abolisher - around $10 Archaeomancer - around $0.20 Grim Haruspex - around $1.30 Imperial Recruiter - around $12 Champion of Lambholt - around $2 Total value: $25.50 Secret Lair x Monster Hunter: The Monsters Nezahal, Primal Tide - around $8 Sarulf, Realm Eater - around $0.35 Vaevictis Asmadi, the Dire - around $1 Ziatora, the Incinerator - around $0.30 Drakuseth, Maw of Flames - around $0.50 Total value: $10.15 Secret Lair x Monster Hunter: The Monsters 2 Wasitora, Nekorus Queen - around $0.50 Kalamax, the Stormsire - around $0.40 Amareth, the Lustrous - around $0.25 Razaketh, the Foulblooded - around $8 Total value: $9.15 Sol Ring is generally inexpensive on its own (at about $1.20), and while it's a collector's item when it comes out in different, special versions, this doesn't really increase the value of the superdrops

He moves the Water Energy from his Manaphy to the Seismitoad, he uses Grenade Hammer to KO your only Yveltal, and he does it all with the most obnoxious grin on his face while you just want to set the nearest Seismitoad-EX card on fire