Why is This Deck?
Hidetsugu and Kairi has been a very fun combo enabler for some time and when coupled with reanimation spells, it can provide a pretty nasty recursive threat and damage outlet to close out a game. This is especially clear when Push // Pull is the card you hit, blasting your opponent for eight life loss and teeing up another round of Hidetsugu and Kairi triggers. The goal is to combo kill our opponent with graveyard recursion that forces life loss with our big demon dragon duo at the center.
Read Before You Play
MTG Arena has a few quirks and one of them is that, by default, triggers are automatically ordered even though players within he Magic rules are allowed to have simultaneous triggers resolve in the order of their choice. 90% of the time, the computer gets the order right and it's no big deal, but with Hidetsugu and Kairi, there is one use case where it fails. If the legend rule causes the creature to die, its enter trigger and death trigger go off simultaneously. You will almost always want the enter trigger to resolve first so you can set up exactly the right spell for the death trigger, but Arena automatically prioritizes this in the other order.
To change this, go into your gameplay settings and uncheck 'Auto Order Triggered Abilities.' Honestly, this is a good thing to have unchecked often because you never know when simultaneous triggers can happen, but given how this deck functions you'll need it unchecked here.
Core Synergies
Liliana of the Veil is one of the strongest planeswalkers in Standard right now and is able to single-handedly take over any game where she's left unchecked. It's handy for the aggro match up as your opponent will need to spend damage to remove her (which is just as good as gaining life) and it's handy in the control matchup because you hit them where it hurts – the hand. She also synergizes with Reenact the Crime amazingly because her discard effect makes sure multiple cards hit the graveyard for Reenact the Crime.
Reenact the Crime is very appropriately named in this deck because the goal is to loop it off Hidetsugu and Kairi to recast the Push // Pull that got the combo started. It also has the utility of stealing your opponent's cards that have been discarded to Liliana or Aclazotz, Deepest Betrayal assuming he's been allowed to attack. One note: try to avoid targeting Hidetsugu and Kairi if you can because it will exile the card and put a token into play. Meaning, you cut off recursion options later unless you have other Hidetsugu and Kairis in your graveyard which, I suppose, is not impossible.
Aclazotz and Phyrexian Arena are both one-ofs in the deck to make sure we can generate some form of card advantage. Having a Liliana in play often results in both players stuck in top deck mode just hoping to find some action and these two cards help by drawing you cards or hating on your opponent's hand. We have other hand hate and card draw effects in the sideboard should the matchup prove amenable to such things.
Can We Talk About This?
Three Steps Ahead is a broken, dumb, stupid, and powerful Magic: the Gathering card and easily the best 'Cancel with set's mechanics' we've seen in a very long time. The ability to hard counter a spell for three mana is fine, but doing so while replacing itself for five is nutty in any deck that can run it. This deck, unlike many others, can take advantage of the second mode, though, by making copies of Hidetsugu and Kairi and looping our combo. If you do this, you'll often want to select the token as the version to keep so that the card finds its way into the graveyard for future reanimations.
Honestly, this is, in my opinion, the best counterspell we have in Standard right now, especially in decks that can't run No More Lies. If you're running blue, you should at least consider making room for it even if it doesn't align with your strategy.
And the Rest
The other cards aren't super inspiring, but they are consistent because they simply keep threats off the board and whittle away at our opponent's resources as we try to set up the combo. Unlike other control decks, our deck is capable of delivering a powerful kill shot on turn five or six and isn't dependent on grinding our enemies out. A little disruption and survival in the early game should be enough to carry us through.
Sideboard Considerations
The sideboard contains many of our existing early disruption cards such as Cut Down and we can simply slot in more if they're useful in the matchup, but there are other callouts I want to mention.
Jace, the Perfected Mind is a powerful win con against control decks or the grindy domain builds because it hits the opponent's library for a considerable amount of mill late in the game when they may not be expecting it. In plenty of matchups, it's not very useful, but if a game is going long, it can be a powerful backup plan.
If you find yourself going up against Aftermath Analyst, simply side these in and mulligan to them in games two and three. I'm not kidding, stripping your opponent's fetch lands out of their graveyard slow that deck to a crawl and often completely eliminate its huge game-ending turn.
Duress and Phyrexian Arena are both here to help against control matchups. If the game is likely to grind, having a Liliana of the Veil and Phyrexian Arena simultaneously will often give you the edge. Duress is also amazing in any matchup where the opponent has counterspells. That last sentence is true regardless of format, by the way, the card just slaps against control because one way or another, it'll strip a counterspell.
Conclusion
Like so many jank brews in current Standard, this deck feels like a good Dimir control deck with an awkward combo stapled to it. Removing the graveyard interaction and the Hidetsugu and Kairi to add in more common threats would probably result in a more consistent deck that plays very similar in most matchups, but the combo is still very satisfying. Until Standard rotates, the huge card pool results in the top decks being what they are and trying to brew against it is challenging, but if you embrace the powerful cards and understand what your opponents are trying to do, you can still have some fun along the way.
Thanks for reading, and happy brewing!
