Set up and build-up is critical. Although a bit meta or out of game, rolling against your players can be used as your build-up. This can entail having your players see you make intelligence or wisdom (insight) checks. Then allowing them to counter with charisma (deception) checks. The back and forth could provide a fun, albeit tense, back and forth for the PWK. Showing your players their foe to use the spell before their final clash can also increase its fairness. Having seen it, they can now prepare for it. As the DM, you shouldn’t be too scared to equip a powerful foe or the Big Bag Evil Guy (BBEG) of your campaign with this spell. Experienced tables would learn to fear trickier spells. The likes feeble mind more than they may complain about a well-placed PWK.