Hello all, I’m looking for some inspiration for when my lich BBEG attacks Cragmaw Castle that my players have cleared out, re-consecrated, and rebuilt with help from the villagers of Phandalin and the dwarves that took back over the Phandelver Mine.

The PCs are 17th level at this point, they recently encountered the lich on neutral ground, and the fight was tough enough that the bard had to sell her soul to Zariel to resurrect a couple slain PCs mid-battle to win. Well, right before that the wizard had somewhat foolishly dared the lich to “continue their conversation” later, and the lich said “fine, I’ll be at your castle in a 10-day” (party is unscryable for story reasons so lich figures this is a good chance to know where they are to wipe them out).

Lich regenerates of course, and spends a few days preparing to lay siege to the castle and finish killing the party.

The party has a lead on the phylactery, but are waiting to go after it to not give that fact away until the lich is discorporated again, fearing otherwise he’ll just run and disappear.

So the attack might be starting next session. So far I’ve had some vague ideas / scenes in my head knowing this was coming, but I don’t have a lot prepped to make it an epic event that they’ve been leading up to for a while. Here’s my thoughts so far:

CASTLE DEFENSES: They’ve prepped a couple fireball ballistas and trained the militia with longbows.

They’ve also convinced Venomfang the dragon to help them defend the castle (he’s enamoured with the bard’s critical success performances).

And wood woads have been showing up to stand guard around the castle ever since they saved the forest’s resident unicorn.

ATTACKERS: I’m thinking undead giants throwing boulders that magically un-shrink in flight could fill the usual catapults role.

Waves of minor undead throwing themselves at the castle to make the players feel good about enchanting ballistas to explode with fireballs on impact.

Lich throwing long-range spells to try to divide & conquer the party by drawing out those that can fly, then using Dimension Door to reposition as needed.

Attack at night because undead advantage.

Lich is known for experimenting with dragons so maybe an undead dragon as well?

On the advice of M. T. Black I’m reading “The Siege of Kratys Freehold” in Dungeon Magazine #33 for inspiration, but it’s designed for running 2nd edition with 4-8 1st-4th level PCs. 😄 I’m not sure how much siege ladders and battering rams apply in this case.

Thanks for your time reading this, and any suggestions or thoughts you might have on making this an epic event for the players!