You could build a power board: a 15-20 card sideboard that can slot into a deck specifically to change the power level only
One Piece TCG booster box hits all-time-low price The Mighty Enemies boosters are the third expansion to focus on One Pieces East Blue saga, as well as threats from across the whole of One Piece
Darkness Pokmon can be weak to Fighting and Grass-type Pokmon, depending on whether they are also Dark or Poison-types and the specific card
Every time its equipped creature deals combat damage, you get two charge counters, and each one can be spent to give your creature +2/+2, shrink an opponents creature by 1/1, or gain 2 life
Kashtira Fenrir, Kashtira Unicorn and Kashtira Ogre will all mess up the opponent's resources, even though the Mitsurugi Deck does not make use of the Extra Deck compared to the more meta decks