As of when this article is being written, Greninja ex's Ultra Rare card has been seeing an upward trend in its value
Note that not all cards that create Bird tokens fall into this category, as its clear that while Hermes, Overseer of Elpis can create a small flock, those are just regular birds
Any deck that makes a bunch of counters in blue should be running a copy of this card
"Tovolar, Dire Overlord" allows the player to draw a card whenever a Wolf or Werewolf attacks, while the Planeswalker "Arlinn, the Pack's Hope" makes it easier to summon more creatures onto the board
hope this helps
[5] The classic example is something like, If I let you resolve your commander will you agree to not counter mine next turn? Basically, both of you get something out of it