Most of the time, Market Gnome's last ability will trigger because it was exiled as one of the components used in the craft ability
Most often this is a mechanical thing, such as Gisela, Blade of Goldnight trying to put a huge clock on the game or Jori En, Ruin Diver trying to trigger her draw effect as often as possible
Crystal Skull asks you if youd consider a four-mana rock if it also gave you Future Sight for an arguably easy to build around theme
This was revealed in an unofficial Reddit post by GuillaumeDuNord
You can easily build around this with effects like Sanguine Bond and Vito, Thorn of the Dusk Rose

Ayara's Oathsworn Beseech the Mirror Beseech the Queen Bogbrew Witch Brainspoil Bringer of the Black Dawn Case of the Stashed Skeleton Coveted Prize Cruel Tutor Cynical Loner Dark Petition Demon's Herald Demonic Bargain Demonic Collusion Demonic Tutor Diabolic Intent Diabolic Intent Diabolic Tutor Dimir House Guard Dimir Machinations Emeritus of Woe Entomb Gravebreaker Lamia Grim Servant Grim Tutor Hoarding Broodlord Hour of Victory Illicit Shipment Imperial Seal Increasing Ambition Infernal Tutor Insatiable Avarice Liliana Vess Lively Dirge Mastermind's Acquisition Netherborn Phalanx Oriq Loremage Profane Tutor Razaketh's Rite Razaketh, the Foulblooded Rhystic Tutor Rune-Scarred Demon Servant of the Stinger Shred Memory Sidisi, Undead Vizier Smuggler Captain Splinter's Technique The Creation of Avacyn The Cruelty of Gix Urborg Panther Vampiric Tutor Vile Entomber Whisper Squad Wishclaw Talisman Witty Demon (playtest)