Thanks guys for your ideas, I should have the basic mechanics explanation by Tuesday. I will also answer all the questions in due time

MrB-
"Maybe besides gold, you can also have the currency "darkness"? ("The depravity and general ickyness of your city attracts some more unsavoury types of adventurers". Or "well versed in evil magic, you mastered the art of summoning dark monsters to do your bidding".) Then at the beginning of the game, you would have to choose how much of each you will get each turn, and get stuck with that amount for the entire game? Like: "6 gold and no darkness", or "2 gold and 4 darkness" per turn.
That would open up the flavour of certain cities being more evil/depraved while others could be more typical fantasy genre type cities. "
I like the idea of having more then one type of currency (currently I have only decided on gold as being one of 2 or maybe 3 forms of currency) which would be decided by a "Town Card" this would be one card that is chosen by the player to represent the town and would have the base currency per turn as well as any special abilities of that town.
"A side deck could work very well! Or if not, maybe just a separate type of card for the main deck would be enough? You could call them "Punishment" or "Sentence" cards or something. =P
These cards should give a bonus while played or in play. For example, if you manage to have your monsters rape a BM and play one of these cards, it might increase your monster morale, adding to the combat strength of your monsters in play."
I really like that idea as well as the prisoner pile idea in fact I am going to implement the prisoner pile in some form.
Ctwo-
I was more heading towards a having to hire BM's opposed to a war of attrition, although I did have an idea to have the players start the game by playing one low cost BM on the field from their initial hand, this would represent the town's current protector. As the game progresses the town would hire more BM to combat the rising amounts of monsters attacking the town. I think you missed that the player controls both the BM's defending their town and the monster's attacking the other player's town.
EDIT:
Ok I have decided on the 3 types of currency
Gold, Soul Gems and Mana Crystals to play a card the player will be required to spend the amount noted on the card being played.
And now for my prototype properties for each type of card:
Battle Maidens
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Name- The name of the BM
Faction- Every maiden belongs to a faction, this may be targeted by other cards
Class- This represents what kind of combatant the BM is, this may also be targeted by other cards
Cost- This is how much the BM costs to play on the field
Attack- How much damage a BM will do in combat
Armour- How much breakable armour the BM has before she starts taking life damage
Life- How much damage a BM can take before she becomes helpless
Resistance- How much a BM needs to be raped before being taken prisoner
Abilities- Certain BMs have different abilities that can be use as described on the card
Monsters
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Name- ******
Species- Similar to Class and Faction of BMs
Cost- ******
Attack- ******
Armour- ******
Life- Same as BM except when reached the creature is dead
Pleasure- How much resistance is removed from a BM when the creature rapes her
Abilities- ******
Event
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Name- ******
Cost- ******
Priority- If an event card is already in play the event being played must have a higher or equal priority to supersede it
Effect- The effect of the card is explained here
Spell
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Name- ******
School- What school of magic the spell is from
Cost- ******
Monster/Battle Maiden/Universal- determines what type of card(s) can use the spell (only spell casters can use spells)
Effect- ******
Special Action
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Name- ******
Cost- ******
Monster/Battle Maiden/Universal- ****** (only non-spell casters can use special attacks)
Effect- ******
Equipment
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Name- ******
Permanent/Consumable - This dictates weather the equipment stays on the BM/monster or is a one time use
Monster/Battle Maiden/Universal- ******
Cost- ******
Effect- ******
Town
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Name- ******
Terrain- What environment the town is located in
Barrier- Determines the amount of times the barrier needs to be hit before it is destroyed and the town is overrunned
Income- Determines the amount of gold/soul gems and mana crystals the town gets a turn to spend
Capacity- Determines the maximum amount of gold/soul gems and mana crystals that can be "stored" in the town's vault to be used next turn
Abilities- ******
Conquest
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Name- ******
Cost- ******
Requirement- How many BM must be removed from the prison to play the card
Effect- ******
(****** functions the same as previously described)