Nathan Long
Zombieslayer
Gotrek & Felix (series) part 12

The forces of the dead, commanded by the infamous Lichemaster, close in, forcing Gotrek and Felix to take refuge in an ancient castle. But as the undead lay siege to the fortress, doom seems close at hand.
Warhammer
novel

Also in:
Gotrek & Felix: the Complete Journey
Gotrek And Felix: Fourth Omnibus