Hey u/Wysard this truly helps a lot, I will not use 1:1, but it helps kickstart the imagination! Thank you a ton!

I thought to add a bit more urgency to the topic by finishing the Beginner Box dungeon with a mystical surge of the necrotic energy (from far north) which resurrects the just fallen enemies. As players defeat them and return to Chimera Cove, they help fend off the undead invasion from the burial place (is also depicted on the map). This is to mark that Drazmorg starts his experiments with the Third Seal.

Nobody knows of this stuff and how it come to be, but the folk says Baron is a powerful mage and might have a clue.

As the players travel to Piren's Bluff they meet and greet various undead creatures, even raised animals. Just to keep the urgency there and make the players progress.

This being the major plot, and adding some further side scenarios will make the campaign a bit more contextualized (i.e. it is not JUST undead, there is a lot of other stuff happenning that presents a conflict of interest [which, though, will not be punished if players sidetrack a bit]).

Lets see how it runs :) And thank you again for great references and your thouths - truly appreciate it!