These use F and exist to tell you what kind of half-deck you're working with before you shuffle two packets together and call it a deck
If youre spending tons of mana on something in Commander, its going to be strong
Gatekeeper of Malakir or Feast of Blood could swap for Geth's Verdict , Gifted Aetherborn or Nighthawk Scavenger could supplement Vampire Nighthawk , Pulse Tracker or Vampire of the Dire Moon could replace Mardu Shadowspear , Blood Artist could replace Cutthroat, Vito, Thorn of the Dusk Rose provides redundancy for Sanguine Bond , Pawn of Ulamog can provide sac fodder for cards like Ob Nix or Viscera Seer , Nullpriest of Oblivion is a flexible way to reanimate beefy monsters like Sangromancer , Vampire Nocturnus , Malakir Bloodwitch , Butcher of Malakir , or Kalitas, Bloodchief of Ghet
"KO" stands for "Knock Out", which means to remove a character from play
Practical tip: tokens read best when the rules box is not fighting the art for contrast