Lets demonstrate this by taking a look at a fairly average Sealed deck I recently played that had 17 lands: Why is this deck playing 17 lands rather than, say, 16 lands (-1 Forest, +1 Arrogant Poet) or 18 lands (-1 Tenured Inkcaster, +1 Swamp)
The most common source of silver-bordered cards like these ones are not MTG crossovers, but instead the joke sets or Un-sets, that are released every once in a while
If you're looking for card games like UNO, either because you love it or need a fun, new alternative, we've got you covered
Skyclave Cleric, on the other hand, is a legitimately workable sideboard card
Magical-land-scenario triggers with Masamune or Ninjas Blades, and some Traveling Chocobo triggers would be great