Cephalid Aristocrat gives you self-milling when its the target of spells or abilities, which
Formats Not Legalstandard Not Legalfuture Legalhistoric Legaltimeless Legalgladiator Not Legalpioneer Legalmodern Legallegacy Legalpauper Legalvintage Not Legalpenny Legalcommander Legaloathbreaker Not Legalstandardbrawl Legalbrawl Not Legalalchemy Legalpaupercommander Legalduel Not Legaloldschool Not Legalpremodern Not Legalpredh Not Legaltlr
The way challenging works is a ready (untapped) character exerts and chooses an opposing exerted character to challenge, and then both cards compare their strength (attack) and willpower (defense) values to each other (meaning the attacker automatically gets hit back by the defender)
most packs will have more Common cards than Uncommon, then Rares and finally if youre lucky Mythic Rare cards too
Final Fantasy X: Summon: Shiva Summons represent one of the most iconic aspects of the entire Final Fantasy series
#7: Force of Negation This inclusion to the list at first can look like a bit of an eyebrow-raiser, but I think this card serves a valuable purpose if the Modern Horizons gives birth to degenerate Turn 2 or Turn 3 combo decks in the Modern format