These tapped creatures can't block until the next turn cycle, and any of your opponent's shock/bond/pain lands are now just slow tapped lands

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 Key to the Side-Door 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

Altered Ego won't enter with any additional +1/+1 counters, and it will just be a copy of the chosen creature
In the Sapphire/Steel deck, youll be On The Case tracking down clues using your Detective characters
They may not be quite as powerful as the ones listed above, but each of them has impacted my experience of the format and has earned a place on my personal top 10 list
Rather than being a one-turn blowout card, Festival is more of an ongoing value engine