Boseiju can deal with such threats like Underworld Breach, Esper Sentinel, Counterbalance, Mystic Remora, and so many others
Drawing four on cast regardless of anything else is great, even if its countered, and Annihilator 4 is going to be a problem to deal with
Instead of equipping one creature in a Voltron style deck, you now want to be equipping many equipment cards across a variety of creatures
Cards that generate additional mana, like Mana Reflection, Mirari's Wake, and Nyxbloom Ancient, can help accelerate your mana production and enable you to cast this powerful monster and other devastating ones like Avenger of Zendikar
Of course, purchasing Jumpstart sets wont quite work for making Booster, Standard or Commander decks and would likely end in sadness for anyone attempting such a feat
Four mana for a one-sided Howling Mine is already not the worst place to start, although that on its own would hardly be impressive