I had a tough decision between two of his worksthis and the Dagobah Swampbut this has always been one of my favorites
Im sure some players will get fancy and play with this effect as the general rule, just for fun
Forces the entire table to change their playstyle
If the spell that's copied has an X whose value was determined as it was cast, the copies have the same value of X

Amped Raptor Ancient Den Arcums Astrolabe Birthing Pod Blazing Shoal Bridge From Below Chrome Mox Cloudpost Dark Depths Deathrite Shaman Dig Through Time Dread Return Eye of Ugin Field of the Dead Fury Gitaxian Probe Glimpse of Nature Golgari Grave-Troll Great Furnace Grief Hogaak, Arisen Necropolis Hypergenesis Jegantha, the Wellspring Krark-Clan Ironworks Lurrus of the Dream-Den Mental Misstep Mycosynth Lattice Mystic Sanctuary Nadu, Winged Wisdom Oko, Thief of Crowns Once Upon a Time Ponder Punishing Fire Rite of Flame Seat of the Synod Second Sunrise Seething Song Senseis Divining Top Simian Spirit Guide Skullclamp Summer Bloom The One Ring Tibalts Trickery Treasure Cruise Tree of Tales Umezawas Jitte Underworld Breach Up the Beanstalk Uro, Titan of Natures Wrath Vault of Whispers Violent Outburst Yorion, Sky Nomad If youre newer to Modern, you may not be familiar with the banlist or the cards on it
He's pretty fun from where I am sitting, n'est pas