When challenged, when challenging, and in a challenge are three different bits of rules text that all apply to different situations
Its a real shame that there are no Shift options for the Incredibles characters in the starter deck
So many of my favourite characters and moments in various games have been captured lovingly in the set such as Vivi casting his iconic Fire magic, or being able to equip the Buster Sword
Im most inclined to suggest a Voltron playstyle for Kefka, since both halves benefit from combat buffs, but honestly, you can build any deck around him
You can then use Pluto's ability again on turn three to cheat out a high-value four-cost card like Lucky, The 15th Puppy or Tinker Bell, Generous Fairy , or combine it with one of this deck's many three-cost characters to effectively play a one-cost location for free