[RULES] Trait: Horde

Rules Summary

• Tally damage done to any member of the horde in a single tally. Any time that tally is higher than the hit points of a single monster, remove a monster. Round monster hit points to the nearest 5 or 10 to make the math easier.
• Whenever the monsters attack or must make a saving throw, assume one quarter succeeds and round up or down depending on the situation. Increase this to half if the monsters have advantage or one in ten if they have disadvantage.
• Adjudicate areas of effect by assuming lots of members of the horde are caught in the area. Small areas hit four, medium areas like thunder wave or burning hands hit eight, large areas like fireball or turn undead hit sixteen. Huge areas like circle of death hit thirty two. If the damage done by an area of effect is close to a single monster's hit points, remove the monsters if they fail the saving throw.

Discussion Video here

Tracking Damage Done to the Horde

• Track damage inflicted to the horde instead of individual monsters in a single damage tally.
• Write down the hit points of a single monster in the horde to keep track of it. Round it to the nearest 5 or 10 to make the math easier.
• When the damage tally takes enough to kill one or more monsters in the horde, remove those monsters, reset the tally to zero, and carry over extra damage.

Tracking Horde Attacks and Damage Output

• Determine how many monsters in the horde attack a given character based on the circumstances of the battle. When in doubt, divide attacks equally among those characters the horde can reasonably attack.
• When the horde attacks, assume one in four attacks succeed. If the horde has advantage, assume half succeed. If they have disadvantage, assume they all fail. Adjust this up or down depending on circumstances. If someone casts shield or has a crazy high AC, remove a couple of successful attacks.

Adjudicating Areas of Effect

When the horde is hit with an area of effect like turn undead, hypnotic pattern, or fireball, adjudicate the results with these guidelines:

• Determine how many creatures are in the area of effect. Assume it's a lot of them.
• Assume one in four creatures in the horde succeed on their saving throws. Adjust this up or down depending on the circumstances. For a truly heroic moment or to make your life easier, assume they all fail.
• If the horde takes damage high enough to kill a single creature, remove all affected creatures. Extra damage doesn't carry over.
• If monsters in the horde are incapacitated, separate them from the main horde and remove them from play.
• Add up any remaining damage done to creatures who survive and add it to the current tally for the horde. If this kills more creatures, remove them, reset the damage to zero, and roll over remaining damage.

Other Tips for Running Hordes

• Use evocative narration to describe the characters' heroic battle against huge hordes of enemies. Hordes are there to show off the might and heroism of the characters.
• Use only one type of creature in the horde. Don't mix up multiple horde types in a single battle. Use the same stat block and create variance in your descriptions.
• As desired, mix in normal monsters with your hordes. A horde of forty creatures might be led by four lieutenants and a boss. Run these extra monsters as you normally would.