Add/Remove from Summary
This event type is gives you the capability to place (or remove) targets into custom summary screens based off of their performance (which you can specify when entering your alert conditions). To set up this alert event, you'll want to be sure to have a custom summary screen already set up.
One of our favorite setups with this alert type is to have two events: one that will add a target to a custom summary, and another that will remove it. Using this alert, anytime a target starts to experience high latency (we have the alert set to look at the last 100 samples, and notify us if 50 or more are over 500ms), that target is moved into our "High Latency!" summary screen. If the target falls back under that threshold, then it's then removed from the summary screen. This gives us a quick view into any of our targets that are currently experiencing issues.