It is not uncommon for 1st Edition cards especially those from early English sets, such as Base Set or Neo Destiny to sell for hundreds or even thousands of dollars due to the limited quantities that have survived
So, why do these cards provoke such different reactions to ordinary removal or counterspells
Dowsing Device / Geode Grotto Rating: 1/10 Unless youre playing artifact creatures and giving them haste, this entire card is so weak and hard to trigger that I dont think itll even do anything relevant
Dragonback Assault is a sweeper that sticks around to give you 4/4 flying dragon tokens on a landfall ability

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Based on the latest market prices tracked on TCG Stacked, Ogre Slumlord is worth about $0.33 USD for a regular copy and $0.54 USD for a foil copy