When a creature is reduced to half its hit point maximum or lower, it becomes Bloodied. It loses this condition if it regains enough hit points to be over half its hit point maximum. A Bloodied creature gains the following effects:

• At the start of each of its turns, a Bloodied creature must succeed on a DC 12 WIS save or flee. If it cannot flee, it surrenders. • When a Bloodied creature fails a save, it can choose to succeed instead. Once a creature has benefited from this effect, it can’t do so again for the next 24 hours, regardless of how often it loses and regains the bloodied condition.

Some creatures gain new abilities when they become Bloodied, making them fight harder or more desperately than before. Some abilities can only be triggered once during an encounter, while others persist for as long as the creature is Bloodied.

• While Bloodied… Traits that have this or similar text in the opening, persist for as long as the creature is Bloodied. • When First Bloodied… Traits that have this text in the opening are only triggered when the creature is first Bloodied in an encounter. If the creature is healed out of its Bloodied state and then made Bloodied again later during the same encounter, this ability doesn’t trigger again.

A creature’s abilities depend on the resources the creature has on hand. If a creature is animal-like in nature, it lashes out in desperation or grows tired as the fight goes on, while humanoid opponents might look for ways to leave combat as they see the fight turning against them. For this reason, some Bloodied features recur, as they are associated with a specific type of creature.

The amount of Bloodied abilities also depends on the creature’s CR. There is no reason for a creature with only a few hit points to have a ton of new possible actions it can do if it’s gonna be defeated in a couple of rounds anyway. Lower CR creatures don’t have as many or as complex Bloodied abilities as a result.

Bloodied abilities can look as follows: Ability Recharge. A trait or action is immediately recharged without the creature having to roll for it.

New Ability. The creature gains a new trait or action while in its Bloodied state.

Strength or Frailty. The creature is made stronger or weaker in its Bloodied state. This can include changes to its AC, speed, or damage resistances.

Trigger Ability. When the creature becomes Bloodied, a unique ability is triggered. The ability only triggers if the creature is able to act it out, meaning that Incapacitated creatures can’t use trigger abilities in most cases. Likewise, if the trigger ability requires a Reaction to fulfill, the creature can’t use the ability if it has already used its Reaction that round.

Death Throes is an effect meant to make the defeat of an enemy stand out as it makes a final show of defiance when slain. It’s a unique effect triggered when certain creatures reach 0 hit points and die. Some creatures, like the balor demon and mephits, already have a Death Throes trait written into their stat block.

Depending on the nature of the creature’s death, the Death Throes might not activate. For instance, if the creature dies from fall damage, is obliterated such as with the Disintegrate spell, or suffers instant death, it’s up to the DM whether the Death Throes occur or not.

Source: ToV Game Masters Guide, Bloodied & Bruised