The first thing we'll note is that Yuriko, the Tiger's Shadow is a ninja, and that she cares about ninjas dealing combat damage to opponents. This points us in the direction of a ninjas tribal deck. She also draws cards without "drawing" them (thus avoiding any draw hate), and uses the cmc of the cards she draws to damage all of our opponents. This pushes us in a direction of caring about cmc for reasons other than mana curve. She also has a unique ability called "Commander Ninjutsu." In order to sort out exactly what all this means and why it is brilliant game design, it might help to look at a classic ninja and understand how ninjas work generally.
As an example, we'll take that most famous member of the tribe, Ninja of the Deep Hours. This ninja can draw cards whenever he deals damage to an opponent which is fabulous! However, he doesn't have evasion himself, and costs four cmc to cast, which is a higher rate than we would want for this type of creature. Indeed, this is the case with most ninjas- they are over-costed and have great on-damage abilities, but don't have evasion themselves to guarantee they can use them. What makes ninjas good is ninjutsu. Ninjutsu is one of those rare activated abilities that function from your hand, in this case during combat whenever you have an unblocked attacker. Ninjutsu then bounces the unblocked creature to your hand and replaces it with the ninja, who then is guaranteed to get through for damage. The ninjutsu cost of Ninja of the Deep Hours is a cmc of 2, which is a much better rate than hard casting it, and which avoids summoning sickness. In essence, your opponents think your attacker is something, only to find out its really a ninja in disguise! Of course, to use the ninja in the first place we need an unblocked creature, which points us to cheap evasive creatures. We want these to be evasive so that they are unblocked, and low cmc so we can get them out early to enable our ninjas, and then redeploy them the same turn if possible to use them to enable still more ninjas. In my old casual days I used Dauthi Slayer and other creatures with Shadow to achieve this, but today we have better options, like Triton Shorestalker for instance.
Of course, prior to Yuriko, there wasn't really a great ninja commander for two reasons. Firstly, there were no legendary ninjas in both blue and black, and thus while Higure, the Still Wind might seem like a great general there wasn't really enough support to field a full deck. Secondly, by default the fact that ninjutsu functions from the hand means that it does not function from the command zone.
With Yuriko then, not only do we have a commander who works well, but one who is perfectly tailored to using ninjas effectively. To begin with, Commander Ninjutsu is effectively an activated ability which functions from the command zone. This means when we use it to put Yuriko onto the battlefield from the command zone we haven't "cast" her, meaning that commander tax doesn't apply. This is great, because our opponents can Swords to Plowshares Yuriko all day, and we can still get her back with a blue and a black as long as we have an unblocked attacker. As such, the only thing Yuriko really has to fear is being stolen with Control Magic spells and abilities or hit with an Imprisoned in the Moon type of effect. The other brilliant thing about Yuriko is that she takes one of the downsides of ninjas, namely, their overcosted cmcs, and turns them into direct damage to all of our opponents. This is especially great because ninjas tend to do poor damage on their own, so this allows us to dish out some real damage to them.
Yuriko's abilities also mean provide a few other guidelines to us. To begin with, she can draw cards like a champion (even though, again, we aren't really "drawing" them), so we don't need as much draw as we would in another deck because its built in. Secondly, mass evasion is ideal here, as bouncing our creatures back and forth all of the time isn't truly mana efficient, so we'll want a way to get lots of stuff through without having to always do so much work. Thirdly, ninjas have great toolbox properties, so employing a variety of tutors helps us to make sure that we have the ninja we need to deal with the problem we have. Fourthly, any ninja gets us a Yuriko trigger regardless of any other abilities, so Arcane Adaptation effects that make all of our creatures ninjas can win the game in a moment. Fifthly, since we care about dealing damage off the top of our library, being able to manipulate that with Scroll Rack type of effects are a huge bonus. Not everything we are playing is a haymaker and our lands will deal no damage, so these cards take the uncertainty out of our game. Finally, we love cards that, like ninjas, have a high cmc but can be cast for much less, like Temporal Mastery and Temporal Trespass. These cards will do tons of damage without rotting in our hands due to delve, miracle, and other abilities that allow us to skirt the cmc. All of these guidelines play to Yuriko's strengths, and will guide how the deck is built.
One other thing to mention is that Yuriko's ability might tempt us to play lots of high cmc cards like Enter the Infinite in order to use them to kill the table, and the pre-MH version did just that. The problem of course, is that these cards are most likely to rot in our hands and possibly draw us early aggro. The key thing to note here is that even if a card only costs 5cmc, if we get even four triggers we've wiped out half of each player's starting life total. 5cmc cards can usually be cast (especially if they are ninjas, miracle cards, or the like), are less likely to draw aggro, and are more likely to synergize with our game plan. For this reason the only high cmc cards I am playing generally are those that like Commit / Memory, Temporal Trespass, Temporal Mastery, and Alrund's Epiphany that we'll ultimate cast for cheaper.
