The game is already fairly challenging (unless you're a veteran who can recall all the MTG sets in order), but it's made more challenging by the broad range of counterspells included
Kitsa has vigilance, prowess, and two abilities - you can tap the otter to draw a card and then discard a card, or you can spend two generic mana and tap it to copy an instant or sorcery spell you control, with the caveat that Kitsa needs three power to do so
Ragavan, Nimble Pilferer Ragavan, Nimble Pilferer would be higher on the list if I wasnt focused on Commander
Most players wont be looking to use one of them on this card
And though it isn't one of the specific examples listed by Magic judges, card size differences could be considered a form of marking
Engaged community and competitive tournaments