Gengar

Flying, lifelink
Delirium - At the beginning of your end step, if there are four or more card types among cards in your graveyard, you may return target creature card with power 1 or less from your graveyard to the battlefield. That creature is a Spirit in addition to its other types, and it has flying.
It apparently wishes for a travel companion. It tries
to create one by taking the lives of others.