The Insta-Monster-Mixture formula (Grand Esker Monster Formula in Japan) is a formula that was created by Escargoon as revealed in the anime episode "The Empty Nest Mess". According to Escargoon, the formula has the ability to turn any creature into a mega-monstrous beast.
Escargoon demonstrated its success by transforming a small caterpillar into a fearsome beast right in front of King Dedede's eyes. Though the transformed caterpillar began attacking them, Dedede was delighted nonetheless, believing he could now create his own monsters without having to spend money buying them from Nightmare Enterprises. The king and his servant snail tried to use the formula to turn Dyna Chick into a monster but failed when Kirby led Dyna Blade to them, at which point she destroyed the formula with her wing and freed her child.
Much later, in the episode "Waste Management", it is revealed that Crowmon found some leftover liquid from the mixture while rummaging through the castle's trash and drank it, not knowing what the liquid's side-effects were. He was transformed into a ferocious beast as a result, but the effect wore off and he returned to normal when he was defeated by the combined efforts of Wing Kirby and Dyna Blade.