Hello! I understand the feeling... you have 3 fields as a condition, and also each of them should be the trigger. Since rule can be assigned to fields or button, and run only when the field is updated or the button is clicked, we may introduce a "Trigger". Attached sample form would be of your help. (COMPLETE if {A is blank} & {B is grater or equal 100} & {C is not blank})
Steps:
1. create new field Trigger. set rules for all 3 fields that set Trigger = 'ON', when the field is modified.
2. add a rule to Tigger: if the 3 conditions you mentioned are filled, then set Result = 'COMPLETE'.
3. Then clear Trigger = ''. Also check 'Don't run remaining rules if the condition of this rule is met'
4. you may also clear COMPLETE, if user modified field(s), and the condition is no more satisfied. So add the last rule to set Result = ''.
