Two-hearted

is a physical mutation that bolsters the player's Toughness and increases their sprint duration by a mutation level based percentage.

Formulas
The following formulas are used to determine Toughness bonus and sprint duration based on mutation level.

Advantages

 * Grants increased Toughness, which increases the player's health and regeneration rate, and factors into certain saving throws
 * Can grant dramatically increased sprinting duration, allowing one to flee a fight or close a gap in melee more easily
 * Gaining Toughness through this mutation can allow one to spend their attribute points on other Attributes

Disadvantages

 * Moderate cost on character generation
 * Relatively low initial Toughness bonus; increases slowly with additional levels