There are many ways to prevent damage that would be dealt to or by a creature. Some effects specify a specific amount of damage (Abuna Acolyte), some will prevent all damage from specific sources or types of damage (the portion of the protection ability of Spirit Mantle that prevents damage), and others will prevent all damage (Soul Parry). However, it is important to note that prevention effects that apply to creatures will only prevent the damage that would specifically be dealt to the creature. This matters with some spells and abilities and when dealing with combat damage from creatures with Trample.

For example, Ghostly Possession will only prevent the damage that is assigned to the enchanted creature. If a 2/2 creature enchanted by Ghostly Aura were to block a Festerhide Boar without any counters on it, the damage that is assigned to the blocking creature would be prevented. The controller of the Festerhide Board would have to assign at least two points of damage to the blocking creature, but could assign up to one point of damage to the defending player. This one point of damage would not be affected by the prevention effect of the Ghostly Procession.