[Suicide Junkie]

Happiness in the system should probably go up a little bit, and on the planet, down a moderate bit.

You'll want to make it that your slave planet is close to, but not rioting, and probably requires some troops to keem 'em in line.

IIRC, you'll only be able to make happiness go down to Indifferent using happiness decreasers, but that may just be for the racial characteristic, not the facility ability.