This allows you to hold up mana and cast the creature only when you want to, which makes it a lot easier to play around board wipes or to exploit opportunities to gain a big advantage
On top of giving them protection, it also offers other spirits flash, which can become handy for some lords that don't have it
The Wind Crystal I'm sure this is exactly the Overrun someone is looking for, in some deck

Release date: 2023-03-15 Guildpact Paragon Invasion of Ravnica Aerial Boost Alabaster Host Intercessor Alabaster Host Sanctifier Angelic Intervention Archangel Elspeth Attentive Skywarden Bola Slinger Boon-Bringer Valkyrie Cut Short Dusk Legion Duelist Elesh Norn The Argent Etchings Elspeth's Smite Enduring Bondwarden Golden-Scale Aeronaut Guardian of Ghirapur Heliod, the Radiant Dawn Heliod, the Warped Eclipse Infected Defector Inspired Charge Belenon War Anthem Invasion of Belenon Invasion of Dominaria Serra Faithkeeper Invasion of Gobakhan Lightshield Array Ephara, Ever-Sheltering Invasion of Theros Kithkin Billyrider Knight of the New Coalition Knight-Errant of Eos Kor Halberd Monastery Mentor Norn's Inquisitor Phyrexian Awakening Phyrexian Censor Progenitor Exarch Realmbreaker's Grasp Scrollshift Seal from Existence Seraph of New Capenna Seraph of New Phyrexia Sigiled Sentinel Furnace-Blessed Conqueror Sun-Blessed Guardian Sunder the Gateway Sunfall Surge of Salvation Swordsworn Cavalier Burnished Dunestomper Tarkir Duneshaper Tiller of Flesh Zhalfirin Lancer Artistic Refusal Assimilate Essence Astral Wingspan Captive Weird Compleated Conjurer Change the Equation Chrome Host Seedshark Complete the Circuit Corruption of Towashi Disturbing Conversion Ephara's Dispersal Expedition Lookout Eyes of Gitaxias Faerie Mastermind Furtive Analyst Halo-Charged Skaab Invasion of Arcavios

Dynaheir, Invoker Adept First thought is making a extra copies of a permanent spell by adding Lithoform Engine to the Dynaheir mix