Leonin Arbiter has been the centerpiece of a Modern archetype for a while now, typically splashing either green or black. But Eldritch Moon has given the deck a powerful blue splash with Spirits Mausoleum Wanderer and Spell Queller.
Both of these creatures exacerbate the mana denial plan that Leonin Arbiter and Thalia, Guardian of Thraben push you toward, meaning your opponent is going to have a difficult time executing their gameplan in a reasonable time frame.
And once they finally get a creature or two on the battlefield, you have four copies of Reflector Mage to clean them up for just long enough to find a Flickerwisp or Restoration Angel and bounce it again. The addition of Reflector Mage is huge for this deck, because it has typically struggled with early creatures that trump your relatively small hate bears. Even a single Reflector Mage can let you attack for four to six damage, at which point your fliers can easily finish the job.
The increased flyer count also helps this deck apply pressure, which has been one of its primary failings in the past. Mana denial outside of very powerful effects like Blood Moon requires you to put significant pressure on your opponent, since given enough time they will eventually draw out of their mana problems, at which point their hand is replete with spells while you will draw superfluous mana denial cards. Being able to establish a flying force of four or five power is fairly easy in this deck and should end most games while your opponent is still stumbling.
The creature-lands you gain with the blue splash also further this plan, since both create flying attackers. Celestial Colonnade has long been among the best creature-lands ever printed, but Moorland Haunt is not to be underestimated. It can easily create three or four tokens over the course of a game, giving you a Lingering Souls worth of value for an increased mana cost that is spread out over the course of many turns.
The two interesting cards in the sideboard are Blessed Alliance and Ephara, God of the Polis. Blessed Alliance has been picking up recently in Modern sideboards since it is versatile enough to come in in a lot of matchups. It's great against Burn and Infect, can handle large creatures in a pinch, and gives you game in some fringe matchups like Bogles, which has increased in popularity given its positive Dredge matchup. (Not sorry in the slightest.)
Ephara, God of the Polis is a powerful card advantage engine against Jund and Abzan, since you can put creatures onto the battlefield with Aether Vial on your opponent's turn and draw two extra cards per turn cycle. Even though your cards are weaker pound-for-pound, that kind of card advantage will still run away with the game quite quickly.
I haven't been a fan of Leonin Arbiter decks in the past, but this one looks more cohesive than the previous iterations and less reliant on gimmicky synergies. No matter what happens, falling back on some good old-fashioned flying beatdown isn't a bad place to be.
- 3 Flickerwisp
- 2 Kitchen Finks
- 4 Leonin Arbiter
- 4 Mausoleum Wanderer
- 4 Reflector Mage
- 4 Restoration Angel
- 4 Spell Queller
- 3 Thalia, Guardian of Thraben