This deck peaked at rank 27 in the Twitch Prime event this weekend. I really thought I was going to hit top 10 but hit a bit of bad luck in the end and had my run cut short.
Xenan Killers is not exactly a new deck, but it hasn't really been touched much since the expansion. This is my take on the deck for the current metagame. I omit Dawnwalkers but otherwise go all in on the Killers package with x4 Xenan Initiation and x4 Dark Return. We also have a full playset of Xenan Obelisks. Overall, I think the deck has a great win rate against both Praxis Tokens and Alessi decks, which are among the most popular decks. It's also generally good against the majority of the field minus control decks, but those are possible, too.
Prioritize building a big board. You can have a great lategame with Twinbrood Sauropods and Auric Interrogators but in general you prefer to establish a quick dominance in the early turns. Blistersting Wasp matches up very well against so many units in the metagame, such as Icaria, all Combrei units not named Valkyrie Enforcer, and more. Banish is awesome vs. Tokens as it hits Obelisk, and one or two more might be correct (though it's not very good vs. many other decks.)
Tips for playing:
1) Make sure you keep a hand with some decent power and early game. You can go without a 2 drop against most decks, but make sure you at least have a 3 drop. Having at least 1 big thing, like a Titan or a Worldbearer, is also good as you don't actually have many big things.
2) Obelisk is really important for this deck. Not only does it activate Auric Interrogator, but you omit a lot of hard removal for more units. You need to win on the board and dominate combat (which is sort of what you'd like to do anyway.)
3) Against tokens, you have a great matchup, but sometimes you may have a hard time actually closing out the game with damage. Worldbearer Behemoth is really good, and sometimes even just big flying Blistersting Wasps.
4) Against any deck that can play Maiden like FJS, save your Vara's Choice for when they play it unless you are 100% positive they're about to play an Icaria on their next turn.
5) Dark Return + Twinbrood Sauropod is amazing. It's even more amazing if you use Xenan Initiation on one. You also can do some cool market shenanigans with Twinbrood Sauropod: if you put one in and happen to get another merchant, you can take it out and get two!
6) If you think your opponent is going to play Vanquisher's Blade at any point, be careful holding back Dark Returns unless you will have an answer for whatever it is they play the blade on. That card hoses you pretty hard.
The deck can obviously be tweaked and adjusted, but as it is, this 80 is pretty decent against the meta. Play tight and play to your outs and you can get a lot of wins. Good luck!