If an activated ability of a card in exile with a brain counter on it references the card it's printed on by name, treat Rex's version of that ability as though it referenced Rex, Cyber-Hound instead
It does, however, ask that you have a creature on the battlefield, where spells like Animate Dead, Reanimate, Exhume, and Unburial Rites do not
There were rumors that Creature Inc
Its cards like these that make Spright a strong contender for best deck in the format, but the remaining two decks overtake it by just a bit in Master Duel
Cards that "represent negative play patterns and interactions that you generally shouldn't spring on unsuspecting opponents", and which would probably be banned if uncards were made legal
But given how long games go with this deck, that wont save them forever, and you can realistically really constrict someones mana if they stumble