It was, and Mab’s fine. (Still waiting for the iOS fix for her busted trait before I put her back in rotation, though…) The question about the fallout to other troops, though, I think has merit.
Is 13 gems too hard if you’re trying? No, and every color but brown has a targeted transform, along with plenty of other generators. Are the conditional effects on some other troops affected by the change powerful enough? No, but they’re already thinking about fixing that:
I don’t see the point of all the moaning. Constructive suggestions for how those troops could be brought up to par would be worthwhile. Complaining about known issues that they already plan to address accomplishes relatively little.
An easy fix to the difficulty of counting would be to have the computer do it. Make a symbol appear in the corner of the pulsing spell image when there are enough gems for the extra turn.
Better still, this would obviate the need for consistency between troops in the number of gems needed, because it would be obvious in every case whether you are getting the extra turn or not. [Alternatively, the symbol could be used to mean any extra turn after a cast - as in goblins, for example - rather than just this particular case.]