Temporary Vitality, often referred to as Temp V, represents a unique form of Vitality that supplements your existing resilience, rendering you more durable and resistant to damage.

Temp V is typically acquired through Spells, abilities or Spells.

It is important to note that Temp V always reverts to zero following a Long Rest.

It's crucial to understand that Temp V does not accumulate, stack, or combine with itself; it remains non-additive.

Example:

A Caster already has 5 Temp V, and casts another Spell giving them 3 Temp V. The 3 Temp V does not add onto to the 5 Temp V, and the creature still has 5 Temp V.

Dev Note:

This is based on a subtle ruling I came across. It also ties into an interesting interaction (or "buff") with temporary vitality.

Certain effects—such as those requiring concentration—only trigger when you actually take damage to your main vitality. If you have temporary vitality active, damage is absorbed by the temporary vitality first, so your main vitality remains untouched. As a result, effects that trigger "when you take damage" (including concentration checks) do not activate unless the damage bypasses or exceeds your temporary vitality.