I read a book, about a party of adventurers fighting a lich and his armies of undead trying to take over the continent, very high fantasy. It has been a long time and details are fuzzy, but it could possibly be in the forgotten realms books.
It had a powerful monk like in D&D, vampires, priests casting spells, colossal leviathan like undead that roamed the land, a mad scientist style necromancer creating all kinds of new experimental undead, like higher vampires and other new things not commonly seen in fantasy(perhaps bone golems and creatures make by combining several different corpses together, as well as animal undead). There may have been armies of different fantasy races fighting the undead as well.
Thats most of the details i can remember. It was likely between 2000-2012 if that helps.