you get a summoning stone or another warlock and use it with the warlock you want targeted, then a friend uses the portal you summon and it summons the warlock.
But if i where you i would just /who and whisper one
If I wanted to talk to an oath breaker there are three or four trying to be my friend on Facebook. Putting a notice here is likely as good a tactic as any to get ahold of a witch willing to be called by that name, either out of ignorance or contempt.
a warlock is a term for an oathbreaker one whom betrays their coven. The term is witch for man woman and child. Witch for those whom are taught and blood witch for those whom have the ability through ancestral lineage, thers a big difference between the two.