Once you reach the phase of the game where you can afford to do multiple things per turn, you need card draw to ensure you keep having things to do (Circle of Power, Fight On!, Travel the Overworld) or at least cards which can be used multiple times (flashback spells, Ring of the Lucii, Shambling Cieth, Relentless X-ATM092)
Doubling X on Villainous Wealth seems like its pretty strong
Now though one of the old guard of card based gaming is set to arrive on tablets around the world and I'm oh so glad it wasn't available to take up all my time while I was at school yes the Pokemon trading card game is coming to iOS
2 Charizard ex 006/165 Charizard ex provides players with the Explosive Vortex attack, which comes at a high cost of four Fire Energy, but then will do 330 damage which can take out nearly all cards in one shot
This can be incredibly strong in Expanded to sabotage anyone who likes to use multiple special energies, like two Double Colorless Energy GRI 166