At the beginning of your upkeep, sacrifice Justice unless you pay {W}{W}. Whenever a red creature or spell deals damage, Justice deals that much damage to that creature's or spell's controller.
2004-10-04
If a single source does damage to multiple targets at once, Justice will add up all the damage done and deal damage to the source's controller at one time (not multiple separate damagings).
2004-10-04
The damage done by Justice is done as a triggered ability, which is added to the stack just after the red creature or spell deals its damage.