Negative temporary HitPoints (5e Variant Rule)
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Negative temporary hitpoints
Negative temporary hitpoints can be caused by spells weapons and abilities.These hitpoints act similar to normal temporary hit points do, and last as long as whatever caused them specifies. Negative temporary hit points do not directly affect health they instead affect only the temporary Hitpoint number. If there are already temporary hitpoints on the target then this number is subtracted from that number. if the number in the temporary hitpoint box becomes a negative number, any healing must first heal enough to remove the negative temporary hitpoints before healing the target's health directly. The negative temporary hitpoints can be removed by adding more temporary Hitpoints than there are negative hitpoints, but these negative hitpoints are not affected by damage unless the damage is dealt directly to the temporary hitpoints.