These are both cards that make your opponent pay mana to do something
Vivi Ornitier The designers got a little carried away with Vivi Ornitier and forgot to put a tap symbol on him
It is also the card type with the least amount of design space, so in my role as head designer, one of the things I've championed has been slowing down the evolution of planeswalkers to make sure we're "squeezing all the toothpaste out of the tube." Because of this, the static ability on Garruk Relentless was a bit contentious
If you dont want to lose games by getting your lands Stifled, PLAY MORE OF THEM
Command Tower is the classic example: Its colorless from a deckbuilding standpoint because it doesnt have colored mana symbols printed on it, but it still fixes you perfectly in-game because it only makes colors your commander actually has
Sheldon Menery was a founding member of the Commander Rules Committee, instrumental in its inception and early development