How do I attack a strongly-defended position?

[IndyPendant]

Hi all.

We're playing in the King game. It's a VP game, with the single VP province the central isle. 3 VPs wins the game. MA Arco has 2 VPs, and in 3-4 turns he'll have the third.

I am the best positioned to stop him--arguably, the *only* one in the game able to. I am MA Ermor, with good gem income, good (but not completed) research, good gold, tiny blood income, I've got tartarians and hordes and hordes and hordes of undead, a great many 'regular' units such as knights and longbowman, tons and tons of thaumaturges, and magic (and mages) of every type available to me.

I just attacked with a horde of exclusively-undead units, and got slaughtered. In. *ONE*. Turn. Now, don't get me wrong, I expected to lose with my initial assault (hence the attack with only undead and a few good leaders)...but not quite so...pathetically. I had expected to do some damage before I was defeated!

The main issue as I see it is that as the defender, Arco goes first. So he has a ton of S-Casters cast Communion Slave, allowing his latter casters to cast some major damage-dealing spells--before I can even get my defenses up. I lost roughly 2/3 of my army in the first turn, including most of my casters--before I even had a chance to go!

We are very very deeply in end-game here, so we're talking a hundred or more leaders involved in the battle, units in the hundreds, gems tossed around like candy, massive battlefield spells, that sort of thing. --Oh, and I also need to besiege his castle and defeat it *after* I win through to the island itself, to keep him from winning! All in 3 to 4 turns.

So. Is there anything I can do? Or do the game mechanics essentially screw me and it's game over? (Did I mention that I have three or four turns to come up with something? ; ) I have some ideas I can try, but at this point I give them a very slim chance of success...hence my appeal to the forums for help.

--IndyPendant.