Chase Rules
My house rules are shown in dark blue. I find that using miniature figures helps when running a chase, so the following rules assume that you are using figures on a grid. Standard combat rules apply except as noted below. Characters that pause to take an action, other than Dash, move a distance equal to their move rate. Most characters use the Dash action and move a distance equal to twice their move rate.
Setup. Determine where everyone involved in the chase is located. The only thing that matters is how far apart everyone is. Place the lead quarry first, then place the others at the appropriate distance behind him. If their locations aren’t pre-determined based on the encounter, you can randomly set the distance from the lead pursuer to the closest quarry at the speed factor of the fastest creature + 5x(1d6) feet.
Determine Initiative. Set initiative order based on position. The lead character is assigned the highest initiative, followed by the others in order of their distance behind him. This initiative order may change from round to round as creatures pass each other. Ties go to the one with the highest dexterity score.
Track Movement. After the lead quarry determines his total move distance – write that distance down so it can be referenced by all players. Don’t move that figure. On each participant’s turn, compare the distance he moved to that of the lead quarry. If they are the same, the distance between them remains the same, so his figure doesn’t move. If he moved farther than the lead quarry, subtract the lead quarry’s move from his and move his figure forward by that amount. If the lead quarry moved farther than he did, subtract his move distance from the lead quarry’s and move his figure back by this amount.
No Opportunity Attacks. No one involved directly in the chase can use an opportunity attack against anyone else in the chase.
Track Exhaustion. You can use the Dash action a number of times equal to 3+ your Constitution modifier. For each Dash action after that you must succeed on a DC 10 Constitution check or take one level of exhaustion. Your speed becomes 0 when you reach level 5.
Pursuer Overtakes Quarry
Attack. If a pursuer is able to move into a quarry’s space, he may instead use a bonus action to perform a single melee attack against the quarry when he is within reach. The attack is made at a disadvantage. Note that the pursuer cannot use this option if he can only move within reach, but could not overtake the quarry if he chose to.
Overtake. A pursuer overtakes a quarry when he moves into its space. He can then use a bonus action to attempt to grapple the creature. Normal grapple rules apply. If successful, both pursuer and quarry are stopped. Rather than grapple, the pursuer may attempt to trip, push over or tackle the quarry. The pursuer has advantage on the attack. As an optional rule, an attack that fails by 5 or more results in the pursuer falling prone.
Quarry Escapes
The quarry can attempt to escape if it is out of sight for all of the pursuers. He makes a Dexterity (Stealth) check and must beat the passive Wisdom (Perception) scores of the pursuers.
Escape Factors
Complications
Roll 1d20 at the end of your turn and compare that roll to the appropriate Chase Complications table. The complication is not applied to your character, but rather to the next character in initiative order. You can spend an inspiration point to negate the complication you rolled or one that effects you. Rather than rolling on the table, the DM may allow a quarry to impose a condition on a pursuer to slow him down. It might be one listed on the table, or one of his own creation. Another option to using a table would be for the DM to declare conditions based on his map or the terrain and the path the quarry takes.
Prone. A complication may leave you prone. To get up from prone you subtract the distance represented by half your move rate from your total move distance.
Difficult Terrain. Each foot of difficult terrain uses two feet of your move rate. So if you cross five or ten feet of difficult terrain you can simply subtract five or ten feet from your total distance traveled.
Complication Tables. The following are Complication Tables that I have created for different terrain types. The first table is a generic complications table that can be used in a pinch, when you just need to run a chase quickly. The tables that follow that one list a complication type for each situation. Look up the type in the generic complication table.
Port Nyanzaru Chases
Berserk Behemoth. A triceratops carting goods is whipped too hard and goes crazy, causing mayhem in the streets. The characters can chase after to stop it, or the beast chases after them. They start the chase 120 feet away from the dinosaur.
Pickpocket. A pickpocket (spy) snatches something valuable from a character and dashes off. The thief starts the chase 90 feet away from the characters.
Racer Unleashed. During a dinosaur race, an allosaurus bucks its rider, tearing through the streets causing violence and destruction. The characters can chase after to stop it, or the beast chases after them. They start the chase 120 feet away from the dinosaur.
Werepanther Hunt. Two werepanthers in humanoid form fire bows at the characters and chase them through the streets. The werepanthers are competing to see who can kill the most adventurers. They start the chase 150 feet away from the characters.
Port Nyanzaru Chase Complications
You run by a pickpocket (spy). Make a DC 15 Wisdom (Perception) check to notice the thief. On a failed check, you lose 5 (2d4) gp.
A box of gardening tools is in your path. Use 5 feet of movement to go around it or make a DC 10 Strength (Athletics) check to jump over it. On a failed check, you fall prone and take 5 (2d4) piercing damage.
A startled merchant drops a bag of gold coins all over the street. You can use your action this turn to stop and pick up 3d10 gp.
A large crowd is in your path. Make a DC 10 Charisma (Intimidation) or Strength (Athletics) check to push your way through. On a failed check, the crowd counts as 10 feet of difficult terrain.
You run into a surly thug. Make a DC 15 Charisma (Persuasion) check to apologize. On a failed check, the veteran chases after you.
A rain basin tips over as you run by it. Make a DC 10 Dexterity saving throw to avoid the spill. On a failed save, you fall prone.
A merchant stall is in your path. You can use 5 feet of movement to go around it or make a DC 10 Dexterity (Acrobatics) check to tumble through it. On a failed check, you fall prone.
A dimetrodon is in your path. Make a DC 10 Wisdom (Animal Handling) check to get by without startling it. On a failed check, it attacks you as you run by (+4 to hit, 9 (2d6 + 2) piercing damage).
A cloud of biting insects is in your path. Use 10 feet of movement to go around them, or go through them and take 5 (2d4) piercing damage.
You startle a deinonychus who chases after you.
+ No complication.
Urban Chase Complications
A large obstacle such as a horse or cart blocks your way. Make a DC 15 Dexterity (Acrobatics) check to get past the obstacle. On a failed check, the obstacle counts as 10 feet of difficult terrain.
A crowd blocks your way. Make a DC 10 Athletics or Acrobatics check (your choice) to make your way through the crowd unimpeded. On a failed check, the crowd counts as 10 feet of difficult terrain.
A large stained-glass window or similar barrier blocks your path. Make a DC 10 Strength saving throw to smash through the barrier and keep going. On a failed save, you bounce off the barrier and fall prone.
A maze of barrels , crates, or similar obstacles stands in your way. Make a DC 10 Dexterity (Acrobatics) or Intelligence check (your choice) to navigate the maze. On a failed check, the maze counts as 10 feet of difficult terrain.
The ground beneath your feet is slippery with rain, spilled oil, or some other liquid. Make a DC 10 Dexterity saving throw. On a failed save, you fall prone.
You come upon a pack of dogs fighting over food . Make a DC 10 Dexterity (Acrobatics) check to get through the pack unimpeded. On a failed check, you are bitten and take 1 d4 piercing damage, and the dogs count as 5 feet of difficult terrain.
You run into a brawl in progress. Make a DC 15 Strength (Athletics), Dexterity (Acrobatics), or Charisma (Intimidation) check (your choice) to get past the brawlers unimpeded. On a failed check, you take 2d4 bludgeoning damage, and the brawlers count as 10 feet of difficult terrain.
A beggar blocks your way. Make a DC 10 Strength (Athletics), Dexterity (Acrobatics), or Charisma (Intimidation) check (your choice) to slip past the beggar. You succeed automatically if you toss the beggar a coin. On a failed check, the beggar counts as 5 feet of difficult terrain.
An overzealous guard (see the Monster Manual (or game statistics) mistakes you for someone else. If you move 20 feet or more on your turn , the guard makes an opportunity attack against you with a spear (+3 to hit; 1d6 + 1 piercing damage on a hit) .
You are forced to make a sharp turn to avoid colliding with something impassable. Make a DC 10 Dexterity saving throw to navigate the turn. On a failed save, you collide with something hard and take 1d4 bludgeoning damage.
+No complication.
Wilderness Chase Complications
Your path takes you through a rough patch of brush. Make a DC 10 Strength (Athletics) or Dexterity (Acrobatics) check (your choice) to get past the brush. On a failed check, the brush counts as 5 feet of difficult terrain.
Uneven ground threatens to slow your progress. Make a DC 10 Dexterity (Acrobatics) check to navigate the area. On a failed check, the ground counts as 10 feet of difficult terrain.
You run through a swarm of insects (the DM choosing whichever kind of insects makes the most sense). The swarm makes an opportunity attack against you: (+3 to hit; 4d4 piercing damage on a hit).
A stream, ravine, or rock bed blocks your path. Make a DC 10 Strength (Athletics) or Dexterity (Acrobatics check (your choice) to cross the impediment. On a failed check, the impediment counts as 10 feet of difficult terrain .
Make a DC 10 Constitution saving throw. On a failed save, you are blinded by blowing sand, dirt, ash, snow, or pollen until the end of your turn. While blinded in this way, your speed is halved.
A sudden drop catches you by surprise. Make a DC 10 Dexterity saving throw to navigate the impediment. On a failed save, you fall 1d4 x 5 feet, taking 1d6 bludgeoning damage per 10 feet fallen as normal, and land prone.
You blunder into a hunter's snare. Make a DC 15 Dexterity saving throw to avoid it. On a failed save, you are caught in a net and restrained. See chapter 5 "Equipment," of the Player's Handbook for rules on escaping a net.
You are caught in a stampede of spooked animals. Make a DC 10 Dexterity saving throw. On a failed save, you are knocked about and take 1d4 bludgeoning damage and 1d4 piercing damage.
Your path takes you near a patch of razorvine. Make a DC 15 Dexterity saving throw or use 10 feet of movement (your choice) to avoid the razorvine. On a failed save, you take 1d10 slashing damage.
A creature indigenous to the area chases after you . The DM chooses a creature appropriate for the terrain.
+ No complication.
Generic Chase Complications
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Complications by terrain type
The headings are:
1d20Â Â Â results of your d20 roll
Complication   This is what causes the obstruction.
Type   This refers to the Generic Chase Complications above.
Aerial Complications
Complications are easier to avoid when you are flying, checks are made with advantage.