The Mysidian Elder card would benefit a spell-heavy burn deck looking to apply consistent pressure on opponents
A Realm Reborn All-Fates Scroll An Offer You Can't Refuse Ancestors' Aid Ancestral Carvings Ancient Cornucopia Ant-Man's Army Ashling, Rimebound Avatar Kyoshi Avengers Tower Bandit's Haul Barrels of Blasting Jelly Baylen, the Haymaker Bender's Waterskin Berta, Wise Extrapolator Blitzball Blooming Blast Boommobile Branch of Vitu-Ghazi Brass's Bounty Bucolic Ranch Buried Treasure Capital City Captivating Cave Careening Mine Cart Castle Doom Cavern of Souls Collector's Vault Command Bridge Common Crook Conduit Pylons Corsair Captain Cryptex Crystal Grotto Cultivator's Caravan Daily Bugle Building Dependable Quinjet Diamond Pick-Axe Discerning Financier Doc Samson, Super Psychiatrist Dragonbroods' Relic Dragonstorm Globe Eccentric Arachnologist Eclipsed Realms Enduring Vitality Fake Your Own Death Favored Fighter Fearsome Ridgeline Firdoch Core Flamekin Gildweaver Flick a Coin Foraging Wickermaw Forgotten Monument Frog Butler Gene Pollinator Gilded Ghoda Gilded Lotus Gleaming Barrier Goblin Glasswright Gold Pan Goldvein Pick Gravestone Strider Great Divide Guide Great Forest Druid Great Hall of the Biblioplex Greedy Freebooter Greenhouse // Rickety Gazebo Guy in the Chair Hardbristle Bandit Helga, Skittish Seer Herd Heirloom
Their robograding approach that uses computers to grade Pokemon TCG cards returns highly accurate grades
The ability still shows up occasionally on the perenial Sea Serpent's replacement: Sea Monster, but I don't expect to see the ability repeated in the new core set this summer, so this ability will have gone the way of the dodo
Other than Basic Lands, you can usually include only one copy of each card
For Control decks, this is a massive deal
