How do you make kill units so open door

[Floooooby]

I wanna make it so you have to destroy 4 crypts before the door opens to carry on the mission. I have the map sorted out, but i dont know how to do this.
HELP

 

[AceHart]

This might give you some ideas:

FourCrypts
    Events
        Unit - A unit Dies
    Conditions
        (Unit-type of (Dying unit)) Equal to Crypt
    Actions
        Set tmpInteger = (tmpInteger + 1)
        If (All Conditions are True) then do (Then Actions) else do (Else Actions)
            If - Conditions
                tmpInteger Equal to 4
            Then - Actions
                Destructible - Open (your door here)
            Else - Actions

 

[Floooooby]

Thanks dude. Im making a very large campaign, ill put u on under the thanks list.