If you do nothing, then you're not using Siege Rhino to its full potential
Ashiok's Erasure Assembly Hall Aven Shrine Banishment Bazaar of Wonders Bifurcate Bile Blight Bloodbond March Cabal Shrine Callidus Assassin Canoptek Wraith Cephalid Shrine Chrome Replicator Circle of Confinement Circu, Dimir Lobotomist Clarion Ultimatum Cornered Market Counterbore Crumble to Dust Cylian Sunsinger Declaration in Stone Deicide Deputy of Detention Detention Sphere Dichotomancy Doubling Chant Dragonlord Kolaghan Dual Nature Dwarven Shrine Echoing Calm Echoing Courage Echoing Decay Echoing Return Echoing Ruin Echoing Truth Endless Atlas Eradicate Evil Twin Exclusion Ritual Extirpate Extraplanar Lens Eye of Singularity Frostpyre Arcanist Godsend Grim Reminder Grizzled Huntmaster Harness the Storm Haunting Echoes Hint of Insanity Homing Lightning Hour of Glory Infernal Tutor Invader Parasite Invasive Surgery Isle of Vesuva Ixalan's Binding Izzet Staticaster Kotose, the Silent Spider Legion's End Legions to Ashes Lobotomy Locket of Yesterdays Maelstrom Pulse March of Burgeoning Life Mask of the Mimic Mechanized Production Mimeofacture Minamo's Meddling Mindreaver Mirror Box Mishra, Artificer Prodigy Mocking Doppelganger
Crucible of Worlds Although a reprint in Core 2019, Crucible of Worlds has not had a real printing since 2007 in Tenth Edition
His +1 ability is an all-purpose, defensive buff that'll give you a temporary advantage, while his -2 ability is a more defensive long-term spell
Archmage of Echoes This is a kind of card we see every so often in a commander precon
Ral, Monsoon Mage / Ral, Leyline Prodigy I give a lot of credit to Ral, Monsoon Mage for having a planswalker's +1 ability before earning the spark, and the cost reduction feeds right into playing multiple instants or sorceries
