Okay, I just ran through the tutorial again and oddly enough, there aren't any events with multiple conditions in them. Suffice it to say, you can have more than one condition to trigger an action, like so:
+enemySprite is visible
+enemySprite overlaps bulletSprite
+enemySprite.Value('shield') = 0
All you have to do is right-click an event condition and select "Insert New Condition," or click an existing condition and click the "+ New Condition" link that pops up.
Argh, sorry for the double-post.