mewtwo pokemon card base set (20/165) [Expedition: Set] Psychic Psychic (10+) Does 10 damage plus 10 more damage for each Energy card attached to the Defending Pokémon Mewtwo - Base Set -

If it stays on the board for even a few turns, the Smothering Tithe Treasure advantage quickly snowballs

Akroan Horse Avarice Amulet Bill Ferny, Bree Swindler Chaos Lord Coveted Falcon Custody Battle Fateful Handoff Fickle Efreet Goblin Cadets Harmless Offering Humble Defector Jinxed Choker Jinxed Idol Jinxed Ring Jon Irenicus, Shattered One Measure of Wickedness Rainbow Vale Risky Move Rogue Skycaptain Rohgahh of Kher Keep Sky Swallower Sleeper Agent Stiltzkin, Moogle Merchant There (split card)(playtest) Treacherous Pit-Dweller Wishclaw Talisman Witch Engine Wrong Turn Yes Man, Personal Securitron Zedruu the Greathearted Zidane, Tantalus Thief

It has Flash, and that means you will need to have three mana available after you play your turn

Also fuels the threshold deck which includes Nimble Mongoose, Mystic Enforcer, and Werebear

Then his -3 is strong as you can build up a graveyard with his +1 or other similar effects that synergize with a plumbed graveyard