I've been away for a while but I've been intermittently keeping track of Magic spoilers and Tiana caught my eye when Dominaria dropped. Her stats and abilities say "Voltron," but I think her real potential is as a Boros control commander. The secret, of course, is that auras enchanting your opponents' stuff will return to your hand as they (or their targets) die. You can use a bunch of Pacifism effects to keep dangerous creatures on lockdown and eke out advantage with enchantment-matters cards. Here's the list I have so far:

1 Tiana, Ship's Caretaker

1 Glaring Spotlight
1 Sensei's Divining Top
1 Journeyer's Kite
1 Scroll Rack
1 Torpor Orb
1 Sol Ring
1 Boros Signet
1 Chromatic Lantern
1 Coalition Relic

1 Weathered Wayfarer
1 Auratog
1 Faith Healer
1 Kor Spiritdancer
1 Sram, Senior Edificer
1 Tocatli Honor Guard
1 Heliod's Pilgrim
1 Mesa Enchantress
1 Nomad Mythmaker
1 Umbra Mystic
1 Ajani's Chosen
1 Archangel of Tithes
1 Brood Keeper
1 Sun Titan

1 Land Tax
1 Sigarda's Aid
1 Ghostly Prison
1 Solitary Confinement
1 Outpost Siege
1 Sigil of the Empty Throne
1 Sphere of Safety

1 Chained to the Rocks
1 Detainment Spell
1 Gelid Shackles
1 Hyena Umbra
1 Darksteel Mutation
1 Eland Umbra
1 Felidar Umbra
1 Soul Tithe
1 Sun Clasp
1 Ward of Lights
1 Bound by Moonsilver
1 Hobble
1 Pariah
1 Prison Term
1 Shifting Shadow
1 Brand of Ill Omen
1 Curse of Exhaustion
1 Faith's Fetters
1 Overwhelming Splendor

1 Enlightened Tutor
1 Fault Line
1 Magmaquake
1 Open the Armory
1 Chaos Warp
1 Leave / Chance

1 Arcane Lighthouse
1 Arch of Orazca
1 Clifftop Retreat
1 Command Tower
1 Dust Bowl
1 Emeria, the Sky Ruin
1 Mistveil Plains
1 Plateau
1 Sacred Foundry
1 Scrying Sheets
1 Temple of Triumph
1 Thawing Glaciers
1 Throne of the High City
8 Snow-Covered Mountain
17 Snow-Covered Plains

1 Earthquake
1 Faithless Looting
1 Replenish
1 Three Dreams
1 Winds of Rath
1 Plea for Guidance

One annoying thing about this deck is that sweepers are a nonbo with Tiana since the auras will die after her because of how state-based effects work. You do still want to run them since go-wide decks are the natural counter to a deck running a stack of Pacifisms. You therefore have to limit yourself to sweepers that don't kill Tiana - that is, mostly red ones that specify "creatures without flying" or ones that deal two or less damage. I went with the former since most token / go-wide decks have ways to boost toughness far past 2.

The other annoying thing with this deck is the major problem with Boros in general: card draw and card selection. You do get to use a lot of tutors in this deck since you're running enchantments, but turn-to-turn card flow is still an issue. Because of that, I went with the Top / Snow lands / Scrying Sheets engine, then tossed in Scroll Rack plus Journeyer's Kite and Land Tax. A few red spells and enchantress effects round out the card draw suite. It would be nice if there were more worthwhile scry effects in these colors, since your draw is either predicated on casting spells continuously or on assembling multi-card combos, but there sadly aren't many cards worth running.