Human Racial Power: Adrenaline (5e Other)
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The human race in 5e Dungeons and Dragons is inferior in comparison to other races, they can't breathe fire, they aren't immune to magical sleep, and they don't have advantages on saving throws versus poison. The only upside to the human race is that they get +1 to any two statistics. But because they have no racial powers, nobody in their right of mind wants to play them unless it's to add variety to the party. Thus, I have an idea to raise humans to a level of equality to dwarves, elves, halfings, and other races. I now present to you this clever plan.
Human Racial Power: Adrenaline
Only Humans and half-humans have adrenaline. In dire situations, adrenaline pumps through the human's veins and grants them superhuman strength and agility if only briefly yet leaving them drained of strength afterwards.
This power is triggered by the human when they have only one hit die remaining (or two if they are level 10 or higher) and they succeed a constitution saving throw of the following:
Barbarians, Fighters, Paladins, Rangers, Monks: DC 5
Rogues, Bards, Clerics, Druids: DC 7
Warlocks, Wizards, Sorcerers: DC 10
(Half-Humans have -5 to save)
The Human has double the normal speed, advantage on attack rolls, saving throws, and all strength, dexterity, and constitution checks for the duration of the power. After the power ceases, the human gains d2 (d4/2) levels of exhaustion to a maximum of 4 levels of exhaustion.
This Idea presented by Greenmaw, Dragonborn Cleric.