This optional rule makes it easier for a creature to be felled by massive damage. When a creature takes damage from a single source equal to or greater than half its hit point maximum, it must succeed on a DC 15 Constitution saving throw or suffer a random effect determined by a roll on the System Shock table. For example, a creature that has a hit point maximum of 30 must make that Constitution save if it takes 15 damage or more from a single source. ##### System Shock | d10 | Effect | |:----:|---------------------------------------------------------------------------------------------------------------------------| | 1 | The creature drops to 0 hit points. | | 2-3 | The creature drops to 0 hit points but is stable. | | 4-5 | The creature is stunned until the end of its next turn. | | 6-7 | The creature can't take reactions and has disadvantage on attack rolls and ability checks until the end of its next turn. | | 8-10 | The creature can't take reactions until the end of its next turn. |