The catalyst for this spike appears to be a near-buyout of the card on July 24th
Theres also The Book of Vile Darkness, which fuses together with Eye of Vecna and Hand of Vecna to create Vecna, an 8/8 Zombie God that lets you draw cards, create zombie tokens and just generally be bigger than everything else
You need to assess your situation and figure out if the payoff is bigger than the danger
1-3 Gold, Silver & Bronze Trophy Pikachu 1998 Lizardon Mega Battle Tournament ($192,000) This Trainer promo card is, as far as we know, the rarest and most expensive promotional winners prize in the current history of the Pokmon Trading Card Game
This is what split second says: As long as this spell is on the stack, players can't cast spells or activate abilities that aren't mana abilities. Basically, the card with the split second ability will always resolve first