Notably, they can't be used to change a creature's creature types
Paralyze In Dominaria United we saw stun counters becoming their own mechanic, and while its true your opponent can pay 4 to bypass this tap down, thats a steep cost to pay in the early to mid game
Goblin Assassin Rarity: Uncommon TYPE: Creature SUBTYPE: Goblin Assassin CMC: 5 Mana cost: USD: $0.60 EUR: 0.47 TIX: 0.04 EDHREC RANK: 11414 (2/2) Whenever this creature or another Goblin enters, each player flips a coin
Ruby, Daring Tracker A mana dork with haste is good value, and having Ruby, Daring Tracker in the command zone could be a nice way to ensure you have some extra mana early in the game
Thats fine if those cheap versions of characters are decent includes in your deck, but theres a whole list of floodborn characters that simply dont have a cheap enough or effective enough early game play to Shift onto