Boros Energy wants to curve out with cheap removal like Path to Exile and Galvanic Discharge backed by sweepers like Wrath of the Skies and Avengers Disassembled, so we prioritize resilient threats and ways to protect our board. Elesh Norn, Grand Cenobite is a devastating top-end that shrinks their entire board with -2/-2 while pumping our own creatures, punishing their token and small-creature strategies. Into the Flood Maw offers cheap, flexible interaction to bounce a problematic Solitude or, if the gift was promised, a nonland permanent like High Noon and buy time. Xenagos comes out since it is not a creature while devotion to red and green is less than seven and requires another creature to provide value, and Hooting Mandrills is a weaker body that doesn't survive their sweepers as well as Elesh Norn does.