The reason why cards spike isn't all that important to today's article, since our focus is on understanding how price spikes actually work and what they really mean, but typically there are two primary reasons why cards get bought out and spike in price
The card in second place is another villain
Effects that reduce the cost of spells reduce the total cost, including any escalate costs added
Beyond just being one of the best, green, not exactly green, cards in existence, Gaeas Cradle is also phenomenally expensive
Enigma Drake is a tournament Staple with an entire archetype named after it
Doubling our Giant damage allows us to close out the game incredibly fast, especially in conjunction with Inferno Titan, which deals six damage with its enters-the-battlefield / attack trigger with Calamity Bearer on the battlefield and can often one-shot our opponent if we have some extra mana for its firebreathing ability