It's a cool idea. I don't think it should be a Force power on Jar Jar, but I like your other suggestions, especially about it affecting your own team members. Anything to make Sly and the B'omarr Monk more useful is a winner, in my book.
Maybe it could be like a reverse Mettle ability: "All characters within 6 squares gain
Unlucky (This character subtracts 4 from the results of saving throws)."
Also, the nitpicker in me needs to clarify:
LoboStele wrote:
We already have CS Yoda who allows you to re-roll failed saves. We also have the Special Ability Mettle which allows you to add +4 when you re-roll a save (which makes Yoda and Even Piell really annoying together, lol).
Mettle only kicks in when you use a Force point to reroll--so it doesn't help with Yoda's CE reroll.