Liliana's Mastery: a little too heavy
Showdowns from the past OP16 dives back into the iconic Marineford, Paramount War and Impel Down storylines, during which well known characters were killed, rediscovered and introduced
You have a surprising amount of targets in the deck: Rose Lover, Komushroomo, Peaskeeper, and Princcessprout, and if you choose to run them, Spore and Glow-up Bulb
However, a strategy purely based around Snorlax needs to have support behind it to properly function: energy denial cards and a bit of luck so that the opponent does not open with just one Pokmon that can easily attack over
Two things
Being able to force a player to discard before he or she has had any chance to play the card just seems too mean, even for black