Full-craftsmanship cards, full-card foils, and strange card outlines are regularly Ultra Uncommon or higher
From there, you can pair these flicker effects with cards like Peregrine Drake, Palinchron, or a basic land (in the case of Ghostly Flicker) for infinite mana, Overwhelmed Apprentice to mill your opponents out, or Venser, Shaper Savant to return all opposing permanents to their owners hands, just to name a few of the possibilities
I like the instant better as you can perform some sweet lines, like sacrificing Putrid Goblin with Skirk Prospector while holding priority to get extra mana available that you can use to cast First Day of Class in response
Full Art EX cards introduced tactile premiums that you could feel
Also, it can inflict damage of its own to your opponent when they activate a monster effect
Sabrina will force the opponent to swap out their Active Pokmon for one on their bench, a strategic move to protect vulnerable cards like Staryu from being one-hit, especially if Misty has not yet been played or failed to hit heads