UR Aggro is a low-curve tempo deck full of cheap cantrips (Opt, Sleight of Hand, Flow State) and 1-2 mana threats like Elusive Otter and Slickshot Show-Off, making Spell Snare and Vicious Rivalry excellent at denying their plan cheaply. Disdainful Stroke catches their rare bigger spells and any Eddymurk Crab cast for a reduced cost that still clocks in at mana value 4 or more. We need to be proactive and interactive rather than grindy, so slow card draw like Winternight Stories and the three-turn Awaken the Honored Dead come out, along with Duress since they have few impactful noncreature spells worth stripping.