are all very powerful archtypes in Nick's cube atm and that would be a very powerful option against them, but not a card that was really correct to maindeck enough to be auto include, hence a great sideboard card, but one that's flexible enough to get played enough to justify its slot unlike something like the Blasts or Chill or Boil etc
It is a special format that is multiplayer, intended to play with four or more people (though can be played with more or fewer players)
Lets imagine you dont have Jhoira on the battlefield, but you want to hard cast one of your bigger spells
The former possibility doesn't really work right now
Go into your next tournament well prepared with competitive mainstays that can go in any Deck, like Ash Blossom & Joyous Spring, Nibiru, The Primal Being, Effect Veiler, and Infinite Impermanence
Sets with both tend to hold attention longer