Honestly, my reason to do this is that Seth mentioned this idea on Commander Clash couple of episodes ago and I’ve been thinking about this for a long time, so I decided to do this before Seth could. Not that there’s that much to do here, as most of this stuff just writes itself, although I bet my approach is somewhat different from what anyone else would have done.
Obviously, Yarok, the Desecrated is commander, but since I do enjoy sabotaging myself in deckbuilding in EDH by coming up with arbitrary limitations to what I’m doing, I’ve also decided to use Umori, the Collector as the Companion, which means that only lands and creatures in the deck.
Obviously, I’ll put in pretty much all the ninjas. Not actually all, but most of them anyhow. In order to make them work, I have plenty of cheap creatures with evasion. Obviously, I’ve tried to emphasize ones with other abilities as well and most of them do have etb-abilities.
I also have some interaction. There’s some limitations here, since these all need to be creatures, but I didn’t even push that very much. Ravenous Chupacabra and Cavalier of Night might be good additions (even with the prohibitive mana requirements of the latter).
Otherwise, there’s some value etb-effects which can often be repeated, as you can always negotiate with others to get opportunities to return them to your hand.
I might have overdone it just a bit with the ramp and you should probably cut some of the duals in favor of basics, but you’ll never get me to admit that!