What’s the castle going to look like?
I have a fort plan with the following:
Front and center is a Firestorm Redoubt, flanked on both ends by the trench walls and those ended in a bunker. Second line is a set of trenches with the emplacements book ended with a pair of bastions. Third line is a void generator and a landing pad behind that.
I have all but one bastion it seems now.
See, you said castle, and I was thinking walls... You need some vertical extent there, make those damned bugs climb...
Considering the amount of city terrain I have that is an option. At least that will keep me safe from the big grounders.
Wyverns and mortars are going to be your best threats against hordes, basilisks are good threats against big multi-wound monsters. Too bad platoons went away, that would make spamming heavy weapons squads for mortars easy. Grenades aren't great this edition, but don't forget them. Grenade launchers and heavy bolters in your infantry squads will probably also be helpful, especially if they're going to be sitting still, and cadian regimental tactics will be helpful for that too, making your men a bit more accurate rerolling 1's to hit.
I tend to use grenade launchers in my original guard squads. I'll make a few HB pairings, I rarely used those and have a ton in reserve.
Think a good core of two wvyerns and two basilisks would work, or too much for 1K?
Considering how cheap guard squads are, you could easily get more wyverns and basilisks in the list. I quick built one for cadian doctrine, with creed, kell, a command squad, 2 wyverns, 2 basilisks, a mortar squad, and 6 GL/HB/Vox squads. All under 1k. That's a battalion list. I think you'll have enough needed to counter whatever your opponent brings. YOu may want to take conscripts to screen your gunline. I'm assuming you'll be waiting for him to come to you.
That's not how I play, I favor more aggressive strategies.
I'm more of a tank commander myself, I've done a few with a battalion before, but I'd prefer tanks and more tanks.
This was an exercise in getting an infantry heavy list with a theme that can hold my attention.
The idea of an old fashioned siege defense force seems neat and also goes along with another project I've almost finished.
So the quick list you dropped is one HQ short a battalion. Not that CC are expensive. I added that and dropped the command squad. That placed it at 972 pts.
What I'm thinking is to also grab a primaris pysker (mage) for some defense and attach it to the tanks so that I can make it their own spearhead and custom up the doctrines, get the catachan loading rule and something else.
Actually I'm going to have to make an inquiry or two for the mage, got an idea that will meet my anime reference requirement nicely.