OK when i put in zagreus's random combat code i fixed it to have no errors. Then i dont know where to put the battle are ar the void or the invisible wall for me to go into a battle and here is the code
mob

//Check battlearea of usr and run randomencounter proc for that area when move
Move()
switch(onbattlefield)
if ("battlearea1")
randomencounter1(src)
return ..()
else
return ..()


//Battlearea as a variable so it can be assigned to the player
mob/var/turf/battlearea



mob/proc

//25% chance of searching for unoccupied area and beginning combat.
randomencounter1(mob/M as mob)
var/turf/battlearea/T
if (prob(25))
for(T in world)
if(!T.occupied)
T.occupied = 1
M.oldlocx = M.x
M.oldlocy = M.y
M.oldlocz = M.z
M.battlearea = T
spawn(1)M.Move(usr.battlearea)
M.oldbattlefield = M.onbattlefield
M.onbattlefield = null
M << "Fight!"
M << "Click on the monster you wish to attack to start"
spawn(1)new /mob/Monster3(locate(M.battlearea.x,M.battlearea.y+4,M.battle area.z))
return 1
return 0





//Maincombat proc called on Click() for the monster. Gives options and stuff.
maincombat(mob/attacker as mob, mob/target as mob)
var/list/CombatOps1 = list("Attack", "Run", "Magic")
var/CombatOp1 = input(usr, "What do you wish to do?", "Combat", "Attack") in CombatOps1
switch (CombatOp1)
if ("Attack")
attack(attacker, target)
if ("Run")
flee(attacker, target)
if ("Magic")
magic(attacker, target)




//attacker chose attack on main menu, see if hit or miss, if hit go to damage proc
attack(mob/attacker as mob, mob/target as mob)
attacker << "You chose to attack [src]"
if(prob(attacker.hit - target.evade))
normaldamage(attacker, target)
else
attacker << "You miss!"
npcattack1(attacker, target)



//usr choses flee on main combat menu, return to oldloc and clear battle vars if success
flee(mob/attacker as mob, mob/target as mob)
if (rand(1,3) == 1)
attacker << "You successfuly run from [target]"
endbattle(attacker)
del(target)
else
attacker << "You failed to run and loose a turn!"
npcattack1(attacker, target)


//You didn't think you'd get a fully working magic system in my demo, did you?
magic()
usr << "Not implemented yet."




//Deal damage
normaldamage(mob/attacker as mob, mob/target as mob)
var/maxdamage = attacker.attack - target.defense - (target.agility / 15)
var/damage = rand ((maxdamage / 2), maxdamage)
if (damage <= 0)
attacker << "You miss! (0 dmg)"
npcattack1(attacker, target)
else
attacker << "You hit [src] for [damage] points of damage with a normal attack!"
target.HP -= damage
npcdeathcheck(attacker, target)



//Time for the monster to attack If miss go back to maincombat.
npcattack1(mob/defender as mob, mob/monster as mob)
if (prob (monster.hit))
defender << "The [monster] attacks you and hits!"
var/maxdamage = monster.attack - (defender.defense / 4) - (defender.agility / 20)
var/damage = rand ((maxdamage / 2), maxdamage)
if (damage <= 0)
defender << "The attack bounces harmlessly off you."
maincombat(defender, monster)
else
defender << "Hit for [damage] damage!"
defender.HP -= damage
playerdeathcheck(defender, monster)
else
defender << "The [monster] attacks you and misses!"
maincombat(defender, monster)


//Return the user to their original loc and clear battle variables.
endbattle(mob/M as mob)
var/turf/battlearea/T = M.battlearea
T.occupied = 0
M.battlearea = null
M.loc = locate(M.oldlocx,M.oldlocy,M.oldlocz)
M.onbattlefield = M.oldbattlefield
M.oldbattlefield = null
M.oldlocx = null
M.oldlocy = null
M.oldlocz = null
mob/proc
//P for player, M for mob. :) Check to see if death and reward stuff.
npcdeathcheck(mob/P as mob, mob/M as mob)
if (M.HP <= 0)
P << "You have killed the [M]!"
P.exp += M.expreward
alert(P, "You gain [M.expreward] exp and [M.wealthreward] money,", "Victory!")
P.wealth += M.wealthreward
endbattle(P)
del (M)
//NPC is still alive, so attack.
else
npcattack1(P, M)

//reverse of the above, 1/2 exp loss penalty.
playerdeathcheck(mob/P as mob, mob/M as mob)
if (P.HP <=0)
alert (P, "You have been killed by the [M]!")
P.exp -= (P.exp / 2)
P.loc = locate(20, 43, 1) //Change this to where you want dead people to respawn
var/turf/battlearea/T = P.battlearea
T.occupied = 0
P.battlearea = null
P.onbattlefield = null
P.oldbattlefield = null
P.HP = 1
del (M)
//Player is still alive, so go back to main combat menu
else
maincombat(P, M)



//Just a very basic level system to make the combat actualy do something.
mob
proc
checklevel(mob/M as mob)
if (M.exp >= M.expreq)
levelup(M)


levelup(mob/M as mob)
M << "You gain a level! You are now level [M.level + 1]!"
usr<<sound('level up.wav')
if (usr.hit <= 100)
usr.hit += rand(5,10)
M.attack += rand(1, 5)
M.defense += rand(1,3)
M.agility += rand(1, 3)
M.evade += rand(1, 3)
M.MAXHP += 10 + rand (5,10)
M.level += 1
M.exp = 0
usr.expreq += 150
usr.HP = usr.MAXHP

mob/var
agility
attack
defense
evade
exp
expreq
expreward
hit
HP
MAXHP
level
oldbattlefield
oldlocx
oldlocy
oldlocz
onbattlefield
wealth
wealthreward


mob
icon = 'player.dmi'

HP = 50
MAXHP = 50
level = 1
exp = 0
expreq = 150
hit = 75
evade = 50
agility = 25
defense = 15
attack = 15
wealth = 100
oldbattlefield
onbattlefield




Monster3
icon = 'Monster.dmi'
expreward = 15
wealthreward = 5
attack = 7
defense = 8
agility = 5
hit = 65
evade = 2
HP = 10
//This is where the main combat is called from
Click()
maincombat(usr, src)


//Really basic stat panel
mob
Stat()
statpanel("Stats")
stat("Hit Points: [HP]/[MAXHP]")
stat("Attack: [attack]")
stat("Defense: [defense]")
stat("Hit %: [hit]")
stat("Evade %: [evade]")
stat("Agility: [agility]")
stat("Level: [level]")
stat("Experience: [exp]/[expreq]")
stat("Gold: [wealth]")
statpanel("Inventory",usr.contents)
return ..()

area
battlearea1
Enter()
spawn()usr.onbattlefield = "battlearea1"
return 1
Exit()
usr.onbattlefield = null
return 1

//Fill the battle areas with invisible wall to prevent player from moving.
//DO NOT put on the actual battlearea (blue) turf though.
invisiblewall
density = 1


turf
grass
icon = 'grass.dmi'
void
icon = 'void.dmi'
battlearea
icon = 'Battlearea.dmi'
var/occupied

I dont know how to make it go into a battle feild by just walking around
Do i have to put the battle field through out the whole world or do i do something else so please help men