sm9 booster box Pokémon Double Crit SM10 Set B One Sealed CHN With a variety of cards in each pack Booster - Pokemon - Tag

This effect was once on an Oranguru card with the name Instruct, which was played on a myriad of decks back then

That's powerful on a two-drop, but not too powerful

Another effect is that once per turn, if you would tribute a monster(s) to activate a card or effect, you can tribute 1 dark monster your opponent controls as if you controlled it

negate the effects of all face-up cards your opponent currently controls, until the end of this turn

During Nezbitt's turn, when he initially activated his Deck Master's ability, he announced that for each Machine-Type monster he discarded (via his ability), his opponent would take 500 damage

It can be casual or competitive, or anywhere in between