Honorable Mention: Training Grounds Training Grounds addresses a different cost players come across in activated abilities
Did nobody know how to evaluate cards or what
This is a Jund (Black/Red/Green) deck focused on -1/-1 counters, a mechanic we havent seen supported properly since the original Shadowmoor block
Selvala's card-drawing ability may read a bit group-hug-y, but we all know who's gonna be dropping the biggest, baddest creatures on the board
Vulnerable, situational and overkill in many of the appropriate situations but cheap, very powerful and able to affect the game on the turn you make him resulting in a card that gets played in about half of the UG(x) creature based decks
The exceptions are cards that require them to exist in the sideboard, like the Companion cards, and technically the Dungeon tokens from the D&D sets