Source: Dungeon Masters Guide
A character might receive a blessing from a deity for doing something truly momentous-an accomplishment that catches the attention of both gods and mortals.
Killing rampaging gnolls rarely warrants such a blessing, but slaying the high priest of Tiamat as he attempts to summon the Dragon Queen might.
A blessing is an appropriate reward for one of the following accomplishments:
- Restoring the most sacred shrine of a god
- Foiling an earthshaking plot by the enemies of a god
- Helping a god's favored servant complete a holy quest
An adventurer might also receive a blessing in advance of a perilous quest. For example, a paladin could receive one before setting out on a quest to slay a terrifying lich that is responsible for a magical plague sweeping the land.
A character should receive only a blessing that is useful to him or her, and some blessings come with expectations on the part of the benefactor. A god typically gives a blessing for a particular purpose, such as recovering a holy person's remains or toppling a tyrannical empire. The god might revoke a blessing if a character fails to pursue that purpose or acts counter to it.
A character retains the benefits of a blessing forever or until it is taken away by the god who granted it. Unlike a magic item, such a blessing can't be suppressed by an antimagic field or similar effect.
Most adventurers go their entire lives without receiving even one of these blessings. There is no limit on the number of blessings a character can receive, but it should be rare for a character to have more than one at a time. Moreover, a character can't benefit from multiple instances of a blessing at the same time. For example, a character can't benefit from two instances of the Blessing of Health at once.
Blessings
Blessing of Health
Your Constitution score increases by 2, up to a maximum of 22.
Blessing of Protection
You gain a +1 bonus to AC and saving throws.
Blessing of Magic Resistance
You have advantage on saving throws against spells and other magical effects.
Blessing of Understanding
Your Wisdom score increases by 2, up to a maximum of 22.
Blessing of Valhalla
This blessing grants you the power to summon spirit warriors, as if you had blown a silver Horn of Valhalla. Once you use this blessing, you can't use it again until 7 days have passed.
Blessing of Weapon Enhancement
One nonmagical weapon in your possession becomes a +1 weapon whenever you wield it.
Blessing of Wound Closure
This blessing grants you the benefits of a Periapt of Wound Closure.