As Specialists lets you choose a creature type, it is just efficient in general and fits decks that focus on Zombies, Demons, Humans, Angels, Clerics, and many others
Whether the new Foundations decks will follow this pattern, or they'll differ from their counterparts from four years ago remains to be seen
Only the Planechase casual variant uses phenomenon cards
Thankfully, none of them stand out at first glance as absurdly powerful, so it's hard for me to guess at which ones will be popular
Gallery and List of Siege Cards Invasion of Alara / Awaken the Maelstrom Invasion of Amonkhet / Lazotep Convert Invasion of Arcavios / Invocation of the Founders Invasion of Azgol / Ashen Reaper Invasion of Belenon / Belenon War Anthem Invasion of Dominaria / Serra Faithkeeper Invasion of Eldraine / Prickle Faeries Invasion of Ergamon / Truga Cliffcharger Invasion of Fiora / Marchesa, Resolute Monarch Invasion of Gobakhan / Lightshield Array Invasion of Ikoria / Zilortha, Apex of Ikoria Invasion of Innistrad / Deluge of the Dead Invasion of Ixalan / Belligerent Regisaur Invasion of Kaladesh / Aetherwing, Golden-Scale Flagship Invasion of Kaldheim / Pyre of the World Tree Invasion of Kamigawa / Rooftop Saboteurs Invasion of Karsus / Refraction Elemental Invasion of Kylem / Valor's Reach Tag Team Invasion of Lorwyn / Winnowing Forces Invasion of Mercadia / Kyren Flamewright Invasion of Moag / Bloomwielder Dryads Invasion of Muraganda / Primordial Plasm Invasion of New Capenna / Holy Frazzle-Cannon Invasion of New Phyrexia / Teferi Akosa of Zhalfir Invasion of Pyrulea / Gargantuan Slabhorn Invasion of Ravnica / Guildpact Paragon Invasion of Regatha / Disciples of the Inferno Invasion of Segovia / Caetus, Sea Tyrant of Segovia Invasion of Shandalar / Leyline Surge Invasion of Tarkir / Defiant Thundermaw Invasion of Theros / Ephara, Ever-Sheltering Invasion of Tolvada / The Broken Sky Invasion of Ulgrotha / Grandmother Ravi Sengir Invasion of Vryn / Overloaded Mage-Ring Invasion of Xerex / Vertex Paladin Invasion of Zendikar / Awakened Skyclave Best Siege Cards Invasion of Shandalar / Leyline Surge Invasion of Shandalars effect is a decent enough recursion spell
