(Initializing the item array)
Event
Map initialization
Conditions
None
Actions
set itRuneTypes[0] = <Less healing rune>
set itRuneTypes[1] = <Less mana rune>
....
set itRuneTypes[X] = <another different rune item-type>
Run (Creating a rune) trigger
(Creating a rune)
Event
None
Conditions
None
Actions
Create 1 item of type itRuneTypes[(Random integer between 0 and X)]
set iRune = (Last created item)
(Acquiring a rune)
Event
A unit acquires a item
Conditions
(Item acquired equal to iRune)
Actions
Remove (Acquired item)
[Do some stuff if you need to, like giving exp to the unit or something]
Run (Creating a rune) trigger