UBR plays Indomitable Creativity and Fable of the Mirror-Breaker, so Annul is live against those and other noncreature artifact/enchantment threats they might bring in. Change the Equation covers their cheap interaction like Fiery Impulse or Make Disappear at mana value 2 or less, and also catches big spells like Indomitable Creativity or Atraxa, Grand Unifier at mana value 6 or greater if red or green (note Atraxa is multicolor including green, so it qualifies). Stubborn Denial is weaker here since many of their key threats (Fable of the Mirror-Breaker, Indomitable Creativity) are noncreature spells they'll often resolve through ferocious anyway, and Get Out's enchantment mode is mostly dead against their low enchantment count, so trim both. Watch for Volcanic Spite and Negate from their sideboard disrupting your own counters.