When Radiant Elemental is already on the board and my opponent plays Celestial Alignment, the radiant Elemental’s effect will be negated. If that radiant elemental has reborn and is destroyed or if another radiant elemental is played, the new copy’s effect will work as expected. For example, I had a radiant elemental on the battlefield and a handful of 2, 1, and 0 cost spells, my opponent played Celestial Alignment, and all spells in my cost 1 despite the Radiant Elementals ability to reduce spells by 1. I gave the radiant elemental reborn, attacked into an enemy minion to destroy the radiant elemental, a new Radiant Elemental was summoned, and all spells in my hand cost 0.