Target changers can't change target of ability-cou

[travolter]

Dinghammer reported:

Effects that change the target of a spell (Deflection, Divert, Imp's Mischief, Misdirection, Shunt, Swerve) currently can't be used on spells that counter abilities, like Stifle and Voidslime (Voidslime can still have its target changed from one spell to another).