Complex sentence: The Twelfth Doctor's on-screen regeneration is the first of the new series to be without the yellow energy obscuring the facial transformation as was done in the classic series clearly showing Smith's face morphing into Capaldi's.
Split into simpler sentences: The Twelfth Doctor's on-screen regeneration is the first of the new series to be without the yellow energy. Obscuring the facial transformation as was done in the classic series, clearly showing Smith's face morphing into Capaldi's.