Bushi Tenderfoot
represents a very intriguing quest to fulfill. A vanilla 1/1 is about as lame as it gets - and creatures are even better today than when he was new - but a 3/4 with Double Strike and Bushido 2 is... about as crazy as it gets for one mana! You can't rely on your opponent helpfully chump blocking with some 0/1 though, so the Bushi will need some considerable firepower to get him through his initiation murder.
Necrobite ticks all the necessary boxes - deathtouch ensures he makes the kill, and regeneration means he lives long enough to flip. Attacking with the Bushi is pretty obvious (or is it? Mind gaaames) so you'll probably need to feign helplessness and then turn him into a deadly blocker. Gift of Doom also does the same, providing deathtouch and indestructibility and coming as a surprise thanks to having Morph.
Of course, you can't rely on one creature alone - and since Kenzo is legendary, you can't even have more than one flipped at a time. Thankfully, there are a number of other creatures who reward you for landing lethal blows. Wight is a good-sized attacker who can reanimate his fallen foes as disposable zombie tokens, ready to be fed to Gift of Doom. Soul Collector flat-out recruits those she bests in combat, and plays nicely with Gift of Doom by representing a second card with Morph - your opponent will have to guess which one he's playing around!
One other thing to keep in mind is that the Bushi need not kill a creature with combat damage. Combine Necrobite or Gift of Doom with a blast of a Viridian Longbow and he can flip via remote control! Even more exciting, Soul Collector can borrow a creature every turn this way. At that point, your own creatures might not even matter as much! You can also take shots at your own High Priest of Penance if he's enchanted by Gift of Doom, taking out a permanent every turn even if your opponent won't touch the Priest with a ten-foot pole.
