Troll war
A problem on large public wikis full of trolls from all factions. Usually characterized by a large number of revert duels going on everywhere.
See w:Wikipedia:troll_war for policy suggestions that may also apply here.
Dedicated troll war
A dedicated troll war is a well-organized attempt to drive off a particular user permanently from all wikis frequented by trolls. Usually it is only against deeply offensive people clearly guilty of libel and persistent sysop vandalism justified only by amateur psychiatry and echo chamber lies. One such dedicated war was against Erik Moeller. However, Larry Sanger, the first chief editor of Wikipedia, claimed that such deliberate activity was responsible for his permanent departure from all Wikimedia projects - this was probably false, as there were many other reasons, mostly economic, for him to depart in disgrace.