Automatically consumed when you are damaged to under half your life points, this portent will restore 200 life points.
The attuned portent of restoration I is the first tier of attuned restoration portent. Restoration portents are items that sit in your backpack and will automatically heal you when you pass 50% of your maximum life points. This particular portent will heal you for 200 life points.
The portent will not be used if you are hit when you are already below 50% of your life points - it is only when you take damage that takes you from above 50% to below 50%.
Although the portent does not have a Constitution requirement to use, to make it you will need a Constitution level of 10.
Only one portent is used at a time, however if you are healed to above 50% and then take more damage that puts you below 50% again, another portent will be activated (if you have one in your inventory).
If you have a portent of restoration and an attuned portent of restoration in your inventory, the attuned version will be used first. Similarly, if you have multiple tiers of either (or both) portents, the highest tier will be used first.
The portent provides its healing effects after you have taken damage. As such, if you take a hit that takes them from above 50% to 0%, the portent will not be used.