Dragon Mage is a passive which gives +increase dmg% for a specific element for a short while after using another element.
Flame Ward is classed as a fire spell, however, after using it whilst having the Dragon Mage passive, it does not always give +increase light dmg% as intended. The +increase dmg% that comes after using Flame Ward is the same as the +increase dmg% given from the spell used before it.
E.g. casting Flame Ward after Fireball gives +increase light dmg% as intended(acting as a fire spell). However, casting Flame Ward after casting Snap Freeze gives +increase fire dmg% (acting as a cold spell). And finally, as you can deduce, casting Flame ward after Lightning Blast gives +increase cold dmg%.
the element type of Flame Ward (which is fire) seems to be ignored, somehow resulting in treating it as the element type of the spell cast before.