Boros Energy swarms the board with cheap creatures and tokens (Ocelot Pride cats, Dalkovan Encampment warriors, Voice of Victory's mobilize tokens), so Brotherhood's End's 3 damage to all creatures wipes most of their board including Ragavan, Nimble Pilferer, Guide of Souls, and Ajani, Nacatl Pariah's cat tokens. Boseiju, Who Endures replaces two Mountain on a land-for-land basis, giving you a way to blow up their own copy of High Noon, Static Prison, or a nonbasic land later in the game. High Noon is a liability here since the opponent also runs it and their aggressive low-curve plan isn't as reliant on casting multiple spells per turn, so it comes out along with one Kaya's Guile which is too slow against this clock. Teferi, Time Raveler is valuable to shut off their instant-speed interaction like Thraben Charm on your turn.