Not new... it appeared in Town Crier 7, p. 9. Here is how it is worded there:
"Magical Aptitude: This skill may only be taken by a warrior capable of casting spells. It may not be used by Sisters of Sigmar or Warrior Priests. The warrior has a keep aptitude for magic and can push himself beyond normal limits to produce a storm of spells. The warrior may attempt to cast two spells each turn as long as he is not in hand-to-hand combat. After attempting the first spell, he must take a toughness test. If he passes he may attempt a second spell that turn or even cast the same spell twice. If he fails he must roll on the injury table immediately with no saves treating Out Of Action results as Stunned instead."
This version of the skill is very close than Klawful's version, but with one important difference: Klawful's version says the model suffers an injury (which would mean a two-wound model would lose a wound) but the TC7 version specifies that a model who fails the Toughness test immediately rolls on the Injury table, so having multiple wounds would not help. As far as I know, GW never modified this skill and the TC7 version is the correct one. I might well have missed a change, though.