The Dark Healer ability heals one damage counter from Snorlax ex between each turn so long as it has a Darkness Energy attached to it, letting you keep that HP constantly climbing each turn
Competitively, its Terminal Period attack is an intriguing win-condition attack, knocking out foes that line up perfectly on damage counters, while Claw of Darkness offers raw power plus disruption
It also brings with it a good number of powerful uncommon cards for you to build your decks with
Making any Treasure when you attack is powerful, and this makes three or four
If you do, remove the words in square brackets.) Search your library for a [basic land] card, [reveal it,] put it into your hand, then shuffle
Many decks play Abilities, like Genesect V [Fusion Strike] in a Mew VMAX deck, and they rely on them a lot too