As the first dual attribute character card, Kid & Killer shows the captain of the Kid Pirates, Eustass Kid, with his right hand man, Killer, beside him
Being playable in any deck but only desirable in decks playing enough creatures to reliably crew it means that an aggressive player will generally end up with the Copter in their deck, and the power, evasion, and card selection that the card offers tends to give any aggressive deck a real shot in the arm
In Limited, where winning is mostly dependent on combat, this wont be too difficult
Not only is Yuna excellent for ramping up your board state with more powerful creatures, but Yuna ensures that any buffed creatures don't go to waste, repeatedly recycling counters to summon an overwhelming stream of powerful beasts
This is also relevant for wicked roles, which have to hit the graveyard for their intended effect