The raids of Undead Jesters, are announced raids and have similar frecuency like the Grynch Clan Goblins raids in December. Raids occur during April fool's month.
The Undead Jesters appear in (Near of Depot and inside of cities):
Ab'Dendriel
Ankrahmun
Carlin
Darashia
Edron
Kazordoon (floor -3, between entrance and depot)
Liberty Bay
Port Hope (west, east and south across river from Depot)
Svargrond
Thais
Venore
Yalahar
They are easy to kill (On level 30+), but you need use Dwarven Ring (Jesters can causes heavy Drunkenness) and Thunderstorm Runes or AOE Damage to kill in groups is the best way.