Design and objectives:
This deck essentially function like a tier 2 version of a jund or abzan deck without green in it that is designed to pray on other midrange decks. By tier 2 i do not mean 'bad' i just mean that it can thrive in certain metas and not in others and it can kinda almost auto lose to certain decks whereas jund and abzan can effectively take on almost any deck with very little variance. Like jund may have a few 55/45 and 45/55 matchups, but mardu has some 70/30 matchups and some 30/70 matchups. It's just higher variance so it's a little more risky to take into a GP or something.
The deck works a little bit heavier on the token aspect than jund and abzan, but not too an extreme degree. Lilliana can discard your lingering souls much like in abzan to gain incremental value. and there is more life padding in the deck, meaning that you can draw more liberally off of dark confidant without it being too much of an issue. The ideal plan is to try and take their removal turn 1 with an inquisition or thoughtseize and slam a two drop a creature can begin to eek out value either in tokens (young pyro, Brimaz and Kalitas) or in card draw (dark confidant) and grind out your opponent with value.
Fatal push rant:
People may question why there isn't any fatal pushes and here is my reasoning: Mardu has the best one mana removal suite in modern and has absolutely no need for fatal push in my opinion. Bolt and path are objectively better than push and have far more targets that push does. Tron is being played a lot recently and bolt is better than fatal push against tron because it increases your clock and adds pressure to your opponent before their synergies come online. It's marginally better vs abzan and jund, but again, even in the bad matchup, you can use it in combination with tokens to kill creatures too big or just aim it at their face. It's almost never a dead card, unlike fatal push. In other colour combinations i think fatal push is decent because of the lack of good 1 mana removal (grixis and sultai would be good examples), but mardu is not one of them.
Best matchups:
Other grind midrange decks like jund and abzan, this deck thrives on. It has tokens to sac to liliana instead of your main creatures and you can discard lingering souls to it's plus 1, vault of the archangel can push through damage through their big creatures and lingering souls is tough to deal with. Every creature in the deck can create incremental value, whereas with jund and abzan tarmogoyf is just a big creature. You can block goyf easily with tokens and with vault out and mana up they just can attack into your creatures at all. The way you lose against these decks is by having your brim killed by their lili, and having no board presence and no lingering souls in hand, essentially getting out valued by lili and put in a top deck situation too early, because jund and abzan thrives in top deck situations due to goyf being good on it's own, whereas you have young pyromancer instead. Essentially drawing too much removal against a lili, or not drawing enough removal for their big creatures. or getting hit by maelstrom pulse and having a bunch of tokens die or a couple or confidants/pyromancers dies, but you can play around that
Your pre and post board game vs burn is heavily favoured and because that you will probably win a decent amount of your burn matchups because the deck already runs, Kalitas, sorin, shambling vents, lightning helix and collective brutality as ways of gaining life. Also Brimaz is a good blocker and inquisition, Lilliana and kolaghan's command are both really good ways of slowing burn down, and once you remove some of the dark confidants and your one of thought seize, your post board looks far better than burn's post board. You lose by either doing a Conley Woods and fetch shock thought seize on turn one, or by drawing all your confidants or misplaying with your fetches and lands. Burn really punishes you quickly for small misplays and it's important to be really efficient and make sure you take the least amount of damage every turn possible whilst ensuring you have double white for Brimaz.
Your infect matchup is super good, because you have a lot of removal and they don't have very many creatures. Collective brutality is also super good against them on the play. The majority of their deck is just small creatures and instants and sorceries, so if you get a collective brutality with a lingering souls in hand, you can jump yourself really far ahead turn two. The only issue i'd say is that you only have one thoughtseize in the main and inquisition of kozilek can't hit become immense. Drawing inquisitions later than turn two often isn't too good in the matchup.
Worst matchups:
Tron, tron and tron. Did i mention tron? The only way you have game vs this deck is if you thought seize or inquisition a bad hand and land a young pyromancer turn two followed by burn and more discard. There's a reasonable amount of sideboard hate in the deck like wear // tear, thoughtseize, crumble to dust and stony silence. So you have some game against the deck game two, but i would recommend that you mulligan a little more aggressively game 2 and 3 against tron, because you need a good hand with at least one of you sideboard hate cards in it to win.
Decks with collected company and hard to kill creatures like multiple copies of kitchen finks and voice of resurgence are also really good against you. And for that i would recommend bringing in some anger of the gods, engineered explosives and your wrath of god from the side. Depending on the type of collected company deck, their may either be loads of 1 toughness creatures like eternal witness, or pretty much any elf in the elf deck, then lingering souls is ok, but in most company matchups it's the worst card in your deck against them. Having kalitas in your opening hand, although a 4 mana creature definitely makes the hand a little more keepable in these match ups because it makes your inefficient removal in the matchup a lot more effecient.
Suicide zoo is also bad for you because they have a large number of high toughness creatures that are more difficult to interact with. Although, accumulating burn in hand when your oponnent cockily goes to 6 when you have two bolts in hand can often win you games, but a lot of decent players may be better at sussing out what's in your hand and not fall into this trap. Lili is really good vs suicide zoo though because it's always a pain for them to have to sac a creature because there often isn't token generation.
Notes: I wrote this a while back when tron jund and abzan were the big three in the meta, and since the meta has changed to include the new eldrazi tron, and the new form of suicide zoo that now looks more like a jund/abzan/suicide zoo deck smushed together, i now need to do some more testing to find out how other matchups play out. this will be a continued work in progress though.