Warband 1:
Leader, The Undying on Armoured Fellbeast

Warband 2:
Easterling War Priest on Armoured Horse

Warband 3:
Easterling Dragon Knight on Armoured Horse

Warband 4:
Easterling Dragon Knight on Armoured Horse

Warband 5:
Easterling Dragon Knight on Armoured Horse

Warband 6:
Easterling Dragon Knight on Armoured Horse

Warband 7:
Easterling Dragon Knight on Armoured Horse

700 points, 7 models, 13 might.

This seems pretty crazy, but not really. You charge in, kill a bunch of stuff with your Dragon Knights bolstered by Fury, and rely on the Undying to hurl troops and transfix heroes for your troops to kill. You can easily kill swarms of troops, while low-level heroes will be run down and bigger things transfixed and killed. Your Dragon Knights will regain might for this, fueling Heroic Combats letting them quickly break an opponent. You have Fury for survivability and Courage, while the Undying will never die.

Because of low model count and speed, shooting should not be a problem. I'm worried about Fight 5, though.

It this just crazy enough to work? I will test it and see what I get, until then, any advice would be appreciated.

Interesting idea, and these are just my thoughts.

The war priest does have fury, but with such few models is likely to be picked off almost instantly and die in one turn (they will likely get the trap). Likewise with your dragon knights a lost combat will probably result in death fury or not. Therefore I would drop the war priest as I do not think it will really work in such a low model count.

The fellbeast is interesting, but again I would drop it. You primary targets will likely have some will points to resist so you are unlikely to stop them in the first few turns which is when you most need to. Sure you can hurl, but at fight 5 they have a good chance to counter with something of their own and a large part of hurling is to get the knock down for your other models to get double strikes, but you will get that anyway. Also do not think of the undying as unkillable. Once trapped and loses a fight those will points will be very quickly stripped in the form of fate. Sure lacking the option to throw horses would be the biggest miss, but I think with the idea you are trying to run it would be better to go without.

Amdur would be great. Acts as banner, meaning on the charge you get 4 attacks plus the re roll. He also gets the reroll himself and has a very handy fight value 6.

This is what I would go with:
Amdur, armoured horse
6 Dragon Knight, armoured horse
Captain, armoured horse, halberd and shield (because not enough for another knight)

Use the captain's might first to heroic march to get to combat fast. Make sure you do as much damage as possible first turn and spend might wherever you can get a advantage. Keep Amdur at the back of the charge and in the middle unless you can see a good pick for him.

This army has 20 might plus the option for nearly all of them to regain through hero kills. You have the potential to kill 60 models in the first (if everyone heroic combated and killed with every attack), which would be enough to beat almost any team.

Even other heroes and monsters can be countered by heroic striking, and with enough might they will eventually run out, although your main aim would be to kill as many of their easy to kill models first to break them and try to reach the victory conditions fast. The biggest problem I see is hurls against you and sorcerers blast. To counter this I would strike versus monsters without might and any monster with might I would still strike but I would heroic combat with all my other models to get them to move first and not be hit by the hurl. I would put my captain and amdur if needed at the front if they have sorcerers blast in order to be able to resist.

A really nice idea and I like where you are going, and could well work a lot of the time. However is it really going to be a fun and enjoyable match (especially for your opponent) as the game will likely be decided after one turn of combats. I would love to know how it goes if you do try this.