The only real rule for the League is that no individual card can be above $50. If a card ever gets that high, it needs to be cut. A lot of this is on the honor system and it is possible certain cards can get that high without us knowing so there might be a couple games played where something went up before we catch it. But this is why this deck doesn't have Duals or Mana Drain for example.
I have had a few decks that were built with a specific purpose in mind and that eventually become permanent decks in my "rotation". Sygg, River Cutthroat, Queen Marchesa, and Gisela, Blade of Goldnight all started off being built for play in League style settings. Marchesa underwent a huge overhaul when things were done but the other two were reasonably close to the current lists. At least in spirit if nothing else.
I am hoping for the same here. I don't expect the deck to survive but I wanted to build one that could. As such, I looked at one of my favorite 3 color combinations that I didn't have a deck for and that was Esper. I technically do have an Esper list in Varina, Lich Queen but being tribal means it is sort of in its own category. I wanted an Esper list that offered a bit more freedom.
The problem is that a lot of Esper generals sort of suck. Oloro, Ageless Ascetic never needs to be cast and I hate that design space, Sharuum the Hegemon really wants to gravitate towards either combo or at least being Artifact heavy and I don't like either strategy. I actually started off with doing Alela, Artful Provocateur for this League (months ago; we have taken a long time to actually get this started) and I changed that into Kykar as I didn't like the Voltron style as much as I thought I would.
Of the rest, none really stuck out to me as something I wanted to build. Other than Yennett, Cryptic Sovereign. I had a Yennett deck built right when she was released and it was fun. So I revisited that list and started trying to update it with the last 2 years worth of cards. When going through the list, I realized I was banking on the Commander a lot more than I typically like to. So I wanted to get away from that a little. Here is where I am now:
Now, the first thing to comment on is that the deck seems a little disjointed. That is, there isn't really a cohesive identity to the deck. I won't say this is by design, but it isn't exactly unintentional either. There are quite a few cards that let me Scry or put things on top for Yennett's trigger. There are a few blink elements to the deck. There is plenty of removal/counters because I am positive more than one person is going to be going for infinite combos.
Most of the creatures are simply ones I liked to play with rather than them being part of a well-oiled machine. I am banking on Yennett to get me draws along with Rocks and Smothering Tithe to get me mana. The overall expectation for winning is just attacking with big creatures. Most creatures do have an odd CMC so I can cast them for free and the ones that don't are there because they seem like they will work well with the other cards in the deck.
I intentionally decided to eschew extra turn spells except one: Expropriate. This is because it is an odd CMC and I have never played with the card so I wanted to see what it could do. Which, honestly, could probably be said for a lot of these cards.
I do hope that over time I can tighten up the themes and the focus of the deck. One major reason I left it sort of open ended to start is that I wanted the ability to simply move in a different direction if I needed to. Specifically, if every other person in the league is running combo (I don't really expect this to happen) I can simply shift into running combo myself. Yennett can help enable a few and Esper has quite a few options for combo if I want them.