Draeca has scrying and greater scrying but in 3.5e you need to scry on a person, not a place. Also, I think the material component for that spell is significant, like a holy water font which I don't happen to have handy. Arcane eyes or the like would be good. I'll see if I have something like that on my list but I probably don't.
Failing that, I like the diversion idea. Here are some diversion thoughts that occur to me:
- Draeca can summon a storm. However, that could be dispelled and could tip our hands.
- Draeca could summon another dragon ally and have him create a distraction on the far side of the army. We could even summon two allies if desired. These are 7th level spells for me. I just have one 8th level and 4 7th levels spells at present.
- I've got obscuring mist; may also have some other distraction.
- We could try a raid near the army with folks who can fly and fly them to the portal after making a disturbance (seems kind of far fetched but it's a thought)
On scrying, if I can cast the spell (I think the material component will prevent that), we could get close enough to see a guard and then scry him once he goes inside the portal building.
In general, if we have to fight at the portal, then we are probably going to lose. We need to do most of our fighting on the other side of the portal in the MFF. So we need to figure out a way to get into the portal building and get through asap. We could manage a little at-portal fighting but if we get stalled at the portal, we may be looking at a worst case scenario where some of us could fly away and some of us could use Draeca's recall but some might be captured or fight to the death.
Some other things that Draeca has that might help:
- With her last level, she can now do an undead damaging burst of energy (8d8 for all undead within 100', fairly low DC save for half damage). It could take down a horde o' little undead and soften up some bigger ones. Costs 2 turnings. She could combine that with a free-action turn against more specific big-undead which ought to chew through a pocket of an undead army fairly quickly. In fact, if the portal is guarded by undead, we probably don't have a major problem. She has 13 or so turnings per day (2 more with eagle's splendor) so this is expensive but probably worth doing.
- Airwalk: not sure how much of the party she could cover but we might be able to airwalk (for those who can't fly) over obstructions, like walls, armies, etc.
- Earthquake: might mess with an army. Would be counterproductive if it destroyed the portal and its building or blocked the dungeon it is in.
If the portal is in a building, maybe some sort of rapid attack like this might be best:
- Summon two dragon allies.
- One attacks the far side of the army
- The second dragon joins the attack group.
- The party airwalks/flies to the roof of the building as steathily as possible
- We bust through the roof and run through the portal, taking opportunity attacks as necessary
- The second dragon provides cover/distraction until we are all through.
- Both dragons go home at that point and we are in the flying fortress
THey aren't likely to want to disable this portal so we probably have time to rush it and use it before they consider turning it off.
If the portal is somewhere in a big castle or underground, we could try variants of this plan.
Thoughts?