Some cards, like Massive Raid, can unleash powerful effects just by having enough creatures on the board
Like most Magic: The Gathering cards, the value of Core Prowler 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 (Mirrodin Besieged)

A Realm Reborn Approach My Molten Realm Ayara, Widow of the Realm Boon of the Spirit Realm Boundless Realms Collision of Realms Constable of the Realm Depart the Realm Eclipsed Realms Fealty to the Realm Genju of the Realm Greater Realm of Preservation Hostile Realm Liliana of the Dark Realms Mirror Room // Fractured Realm Mirror Room // Fractured Realm Prison Realm Realm Razer Realm Seekers Realm of Koh Realm-Cloaked Giant Realm-Cloaked Giant Realm-Scorcher Hellkite Realmbreaker's Grasp Realmbreaker, the Invasion Tree Realms Befitting My Majesty Realms Uncharted Realmwalker Realmwright Rise of the Dark Realms Roon of the Hidden Realm Sarulf, Realm Eater Shield of the Realm Sovereign's Realm Sustainer of the Realm Sword of the Realms Teferi's Realm Touch the Spirit Realm Underrealm Lich Wrenn and Realmbreaker
However, I think theres more merit to these sets now than just attempting divination through them
For personal collections, this is often the sweet spot