With Sparkling Unicorn in play, Serra's passive healing effect seems not affected when it heals creatures. It correctly heals Serra by 2, but heals the creatures only by 1 point.

I got in play my Unicorn, which blocked a 2-power creature in the Opponent's turn. Then, at the begginning of my turn as Serra, her passive triggered, healing myself 2 points, but healing the "wounded" Unicorn only by 1 point. Considering it is a 3/3, the effect should have returned It at full toughness.