King's Landing.

If it is not Winter, Lion's Gate gains: 'Any Phase: Kneel Lion's Gate to discard 1 power from a non-House card in play. Then, give that card a Trait of your choice until the end of the phase.'

Does the target of this card have to have a power on it to be able to give it a designated trait?

Thanks!

Yes. You have to discard a power from that card in order to give it a Trait.