The biggest examples are the extra combat interactions
For example, Concealing Curtains mentions in its rules text that you can only activate its transform ability as a sorcery, so you cant transform it at an instant speed
Kambal, Consul of Allocation Two life lost and gained sounds insignificant, but it only takes a few turns with Kambal, Consul of Allocation to garner a meaningful life advantage
If youre lucky, you can chain several copies of Persistent Petitioners together for one huge turn
The artwork of the cards has its own fandom and many collectors take more interest in it than the game itself, with original artwork exchanging hands for vast sums
I personally just sang the praises of Brudiclad, Telchor Engineer a few weeks ago, but I think they are the biggest success of this deck