While the last plan is waaaay better than anything else we had. I still don´t like the thought of doing something they expect. (Like facing them on a open battle.) I suggest, something...more bolder...and risky. But if done perfectly. It will be beautiful:
Realm
Mostly stop what you are doing. And start massive worship and sacrificial rituals. Almost everyone should do this. Dedicate all this power to ourself and the army.
Attack the keep - preparation]
While its very hard, almost impossible to attack the keep from the sides, why not do it from the ground and the sky? Demonstyle.
Have black imps dig a tunnel under the keepyard. Give them help from the rest of the army/yourself if its possible. This should be done as fast as possible.
Have green imps creating illusions of our army preparing to fight on the hills.
Have KY search and destroy magical defence spells, especially the ones who might aleart them of the tunnel.
Have Dal'Kahh create and lead a special force with the misson of killing scouts as stealthy as possible.
Have Ky offer resorces for the mercs who joins us/does not fight.
Attack the keep - battleplan
When the tunnel is ready. Attack during the night. Have Dal'Kahh lead the first round of troops (of his chooise) entering from the now visiable tunnel. Still as stealthy as possible.
Orders:
Kill of archers/other guards in the keep. Try to stay undetected for as long as possible. If possible, secure and open the gates.
The second round should be lead by Ky himself. Pick 20 or so of the best armored cultist to join you.
Primary orders:
Find and kill the priets before they can organise. Remember that they are weak individually. If we can keep them for organising, they will be a fairly easy prey.
Secondary:
Find and kill knights.
Now we have to assume that they have detected us. Send in the third round of troops:
All 20 Amberärsh Packs and 25 Giant Rat Packs.
Primary Mission:
Create chaos. Kill sleeping soldiers.
At the same time, send in the Titaneghould and if the dragons can carry them: Some Armoured Baneghoul aswell.
Mission:
OMONOMNOMNO, and KILLKILLKILL.
Let the Dragons and red imps give us support from above afterwards. Killing archers and so fourth.
Now let the rest of our army come fourth. Both from the tunnel and hopefully from the secured gate.
Have catapults create further chaous by bombarding the keep from afar.
Are you crazy?! Attack the KEEP?! Why?!
Well, I am a bit crazy, but I have a few reasons why I think this is a better idea than open battle:
We will be facing less men, some of them will sleep.
We will have the element of suprise, I mean, who whould be dumb breave enough to attack a keep with twice the ammount of defenders?
While they know we are dangerous, they still expect us to fight wars like normal humans do. I find it hard to beleve that they expect us to have imps dedicated to dig tunnels. Or dragons who will drop huge ghouls on their faces.
They wont be mustered, this is crucial, good luck organising a magical defence when most of you just woke up. And the knights will be unarmored. (They only bring their armor when they fight, and it takes extremely long to put them on)
Its way easier to create chaos in an unorganised keep than in an open battle where all their troops are ready to fight and are in formation. And we live on choas.
Its demonic and fun!
The most crucial part of this battle is the digging of the tunnel without they understand what is going on. If they find out about the tunnel, its easy to reverse back to open battle plan.
I know that the plan is far from perfect, and will need a lot if further planning to actually work. But, why not give it a shot?