Arcum Dagsson [Coldsnap] FL if the negated effect can

if the negated effect can be activated

Must first be Special Summoned with "Rise of the Snake Deity" and cannot be Special Summoned by other ways except by its own effect

cloaking everything in deep crimson

While your opponent controls only 3 monsters

Flashback—Sacrifice a creature

Arcum Dagsson [Coldsnap] FL if the negated effect canSet: Coldsnap Type: Legendary Creature Human Artificer Rarity: Rare Cost: {3}{U} {T}: Target artifact creature's controller sacrifices it. That player may search their library for a noncreature artifact card, put it onto the battlefield, then shuffle their library. "Artifice sundered the world. It shall not again wreak such sorrow."