Fynn is a 1/3 Human Warrior with Deathtouch, and whenever a Creature you control with Deathtouch deals combat damage to a player, that player gets two Poison Counters
Just like how those clamouring for Hogaak, Arisen Necropolis or Faithless Looting to get banned in Modern a couple of months ago should have been registering the deck all along, if you want to win and genuinely believe a card needs banning in Pioneer, then you should be playing it and trying to break it
Assuming it enters with less than seven loyalty, it doesnt enter as a creature
My initial assessment of Oko, Thief of Crowns was that its fundamental play pattern was so strong that it would have to be great in Standard, and I even suspected that it might have a place in Modern
Narset, Jeskai Waymaster Step aside, we have a new Storm Commander