Back and there again: Battle of Five Armies with Oathmark

Some time ago, I discussed gaming the Battle of Five Armies using Hordes of the Things. I want to return to that theorizing, but since my friends and I have been playing Oathmark for the past year or so, let's talk about using that ruleset to recreate the scenario from the book version of The Hobbit.

For convenience, we'll go with a figure scale of 1:20, meaning one miniature represents around one score of participants in the battle. Single figures represent certain leaders or other characters along with their bodyguards/companions/retinue.

BATTLE OF FIVE ARMIES

  

Dwarfs

Dwarf King (Thorin & Company)

Dwarf Prince (Dáin Ironfoot) with 9 Dwarf Linebreakers

15 Dwarf Soldiers

Men of Laketown

Human Captain (Bard) with 9 Human Soldiers

Elves

Elf King (Thranduil) with 19 Elf Warriors

20 Elf Spearmen

10 Elf Archers

Others

Human Spellcaster 5 (Gandalf)

Indrik (Beorn)

5 Gargoyles (Giant Eagles)

5 Gargoyles (Giant Eagles)

Goblins

Orc King (Bolg) with 4 Orc Warriors (huge goblin bodyguards)

20 Goblin Soldiers

20 Goblin Soldiers

20 Goblin Soldiers

20 Goblin Archers

10 Goblin Wolf Riders

10 Goblin Wolf Rider Scouts

10 Wolves

5 Gargoyles (giant bats)

Set-Up

Use hills to make a L shape, with each leg about 36" long with the apex to the north. Put some rough ground about 8" across in between the two legs of the L (about 15" from the apex) to represent the ruins of Dale. Place the elves and Gandalf on the left (western) leg of the L. Thorin and co. are at the apex, behind a defensive fortification. The rest of the dwarves are on the right (eastern) leg closest to the middle, and the men of Laketown on the outer end of that hill. All units are facing inward, and the ground behind them is considered impassable except as noted below. Beorn and the Eagles are not placed at this time.

Goblins deploy in the valley within 12" of the south edge of the map and at least 12" away from any elevation.

Special Rules

To represent the vast hordes beseiging the Lonely Mountain, any Goblin unit (except Bolg and his bodyguards) that is destroyed may attempt to come back the following turn. If the destroyed unit activates, it uses one action and may take one action after placement. Units may not be placed within 3" of an enemy unit. Roll to determine location:  

1        no placement this turn

2-4      south edge of map

5        left half of western hill

6        right half of western hill

7        left third of eastern hill

8        middle third of eastern hill

9        right third of eastern hill

10       player's choice

Beginning on turn 5, any unit of Giant Eagles may be placed on the western edge of the map with a successful activation roll and may then take two actions.

Beginning on turn 7, Beorn may be placed on the western edge of the map south of the hill with a successful activation roll and may then take two actions.

Outcome

The game lasts until either all characters on one side are destroyed or until the Goblins move at least two non-flying units into the fortification where Thorin is initially located.

***

I think that pretty much covers everything except Gandalf's spells. I don't see him using fireball, so I wonder what magic I should give him for this battle. Any suggestions?