When an item with this property is given:
- The Player's SpawnHealth is boosted by this amount. Healing items will then heal up to the new maximum.
- Boost items such as the Health Bonus or SoulSphere will have their maximum attained health (Inventory.MaxAmount) effectively boosted by this amount.
Lack of this feature is pretty much the only thing holding back my "Skulltag compat pack" for (G)ZDoom. (The UpgradeStamina method has very undesirable effects, such as fully healing, and there's no change to Health Bonus behavior either.)