I would probably template the Blade-licker demon to care about permanents going to the graveyard instead of being destroyed because having to track whether something that dies was destroyed or not seems painful, and also a lot of layers are not terribly aware of counts as "destroying" and what doesn't
The Mirror Breaker has fallen off in Modern and other competitive formats, but its still a favorite in Commander decks
Uniquely, the character art on each extends all the way to the borders of the card, displaying more of the surrounding scene and making for an overall brighter, more colorful display piece
So, for any given Limited Card, each team could include 1 copy in either Duelist's Deck, making a total of 1 copy that team can use
Those amounts are then doubled to 4 and 6, respectively.
However, these cards are occasionally self-sufficient, and Melmetal ex is an intriguing option for players who like to set up the board throughout a slower game