Ok so he seems brutal and for those unfamiliar he reads
Pay X resource points, KO Jericho >>> If the cost of target character an opponent controls is less than X, move that character to your front row. (You control that character.)

Ok so say you pay the points and ko him and choose a green lantern of some sort. Say in response I ko the target with emarald Dawn does Jericho's power become targetless or could he retarget it to a new Lantern on my side?

Targets are chosen on announcement of an ability if I'm right, so the person playing jericho would be screwed even more then playing jericho's ability would be telegraphing.

The target is chosen when the costs are paid. That means that the opponent can potentially use another means to remove the character before Jericho's effect resolves. If that is done, Jericho's effect is negated, since the target no longer exists. A new target is not chosen, and the costs are not refunded. So, if the opponent can do something like Emerald Dawn, Swift Escape, Blackgate Prison / Arkham Asylum, etc. to stop it, you're left high and dry.

wow...the big j had soo much potenetial..and just like that he is wasted...to live life in the fast lane so much is just not healthy.

With the Underworld, he can still steal a 7-drop on turn 8 just by making a Dark Embrace... he just requires the proper tech... ^_^

The fact that his ability can be negated would not be my concern, rather that you are sacrificing a full two turns to take advantage of his ability.