They all have the word Mox in the name , and their art represents a gemstone or precious metal sometimes held by a pair of hands
While Rhys is vulnerable at 1/1, and his ability is quite expensive, his low mana cost makes him easy to weave into a turn, forcing your opponents to answer him immediately or else
They often have large stats, high mana values, and since they're usually blue creatures, and blue isn't supposed to get large creatures easily, they often come with drawbacks
Since October, Ive been running this Doctor Who pairing as my Grixis upkeeps deck
The graveyard hate side of this is definitely not irrelevant either, making this almost like a new Deathgorge Scavenger and perfect for all sorts of different decks beyond just Mono Green Aggro