Mob Event Triggers are different to Spawner Triggers and are used for starting Mob Events in various ways ushc as just listening to the random event starter or through regular intervals, etc.
array[Spawn Condition] conditions
A list of spawn conditions that are required for this event trigger. Useful if you want different triggers to use different conditions rather than just the base mob event conditions. Default empty.
Determines how many Conditions must be met. If 0 or less all are required. Default 0.