Validation rule to make Multi select picklist value required based on selected value of controlling picklist

Below formula helps to requires the Multi select picklist value  based on selected value of controlling picklist.

// Call_Outcome__c --> Controlling Picklist field 
// Call_Sub_Outcome__c --> Dependdent Multi Picklist

AND(OR(ISPICKVAL(Call_Outcome__c, 'Detailed Call'),
ISPICKVAL(Call_Outcome__c, 'No call')), 
ISBLANK(Call_Sub_Outcome__c))