All in all, the one-of-one One Ring is up there with one of the games best marketing campaigns, arguably even the best, and we can expect much more of this kind of thing going forward.
I'll touch on a few of my favorites
Whenever Frodo, Determined Hero enters the battlefield or attacks, you may attach target Equipment you control with mana value 2 or 3 to Frodo
Rakdos, the Muscle, if you look closely enough, only has one red pip
We get a decent attacker - 5/5 First Strike - but it's the fact we get to double our damage output while halving anything we take that really makes it
You can also win with the alternate win conditions of Felidar Sovereign or Test of Endurance , which automatically win the game if you have 40 or 50, respectively