Altanak, the Thrice-Called Anara, Wolvid Familiar Brokkos, Apex of Forever Brokkos, Apex of Forever Fortune, Loyal Steed Gahiji, Honored One Galian Beast Illuna, Apex of Wishes Illuna, Apex of Wishes Kaheera, the Orphanguard Kethek, Crucible Goliath Kona, Rescue Beastie Lagorin, Soul of Alacria Loot, Exuberant Explorer Loot, the Key to Everything Loot, the Pathfinder Marath, Will of the Wild Migloz, Maze Crusher Nethroi, Apex of Death Nethroi, Apex of Death Nyla, Shirshu Sleuth Otrimi, the Ever-Playful Questing Beast Ragnarok, Divine Deliverance Red XIII, Proud Warrior Slinza, the Spiked Stampede Tayam, Luminous Enigma Uril, the Miststalker Uurg, Spawn of Turg Yannik, Scavenging Sentinel
Like most Magic: The Gathering cards, the value of Grim Initiate depends on a few consistent factors: its rarity, the printing and finish (regular or foil), its physical condition, and the set it was printed in (War of the Spark)
Ardyn, the Usurper Ardyn, the Usurper asks for quite the mana investment, but the demon tokens it creates are massive threats thanks to all the keywords it adds
On top of that, the earliest copies of headliners from each set may sell for astronomical amounts, both because of the prestige of a low-numbered copy and the fact that some collectors may want them as soon as possible