These are my thoughts (it make sense to quickly skim the article linked to familiarise with the basic rules adjustment).
Firstly let’s assume that the main pursuers are a pack of wolves, and the PCs are in some kind of horse pulled arrangement. Either a covered wagon or a carriage type effort.
In my rules there is a pilot / driver who decides how aggressively or defensively to drive the vehicle, and to obtain a benefit makes an opposed check against the pursuers. This allows the whole of the group to either:
- Gain advantage on stealth checks to hide
- Gain advantage on attacks against a single enemy
- Impose disadvantage on attacks from all enemies against the heroes
The most appropriate skills here would be for the pilot to roll Wisdom (Animal Handling)though I can also see a Dexterity (Animal Handling) coming into it if its really fast and frenetic. I’d be tempted to keep the check the same throughout the chase though to avoid confusing players.
In addition, it is the driver that rolls to see whether a hazard is encountered. Talking of which, here are some hazards that might be encountered…
Chase Hazards in Barovia
At the start of each round the driver rolls a d20 and the group encounter the following hazards. I usually rule each hazard can only be encountered once, and a duplicate result is simply not a hazard.
1 – The PCs encounter a slumbering pack of zombies in the middle of the road. The driver must choose between evasive manoeuvres or ploughing straight through. Either requires a successful Wisdom (Animal Handling) check against DC15. Passing the check means they get through without issue, but failure in evading tilts the wagon drastically causing disadvantage on attack rolls from PCs on it. Failure on ploughing through means a zombie gets caught up in the wagon somehow and starts to lash at the players. The zombie is at half-health because of the collision however.
2 – The road spills out onto the side of a ravine, and the track becomes very narrow. It takes a Wisdom (Animal Handling) DC10 check to get through it at full-speed. If the check is failed the wagon moves at half-speed this round (possibly allowing pursuers to get even closer).
3 – The road splits into a high and a low road. The driver needs to quickly decide which to take. The high road is exposed but gives a advantage to the attackers. The low road is covered granting 50% cover to defenders. The roads rejoin at the end of the round.
4 – A thick cloud of bats swarms out of the sky tearing into the wagon. Each PCs takes d4 bludgeoning damage as the small creatures thud into them.
5 – There’s an abandoned barn just off to the side. Low and long the threshing barn has a wagon sized door at either end. A successful Wisdom (Animal Handling) check vs DC10 allows the driver to head in. The pursuers, wary of human-built constructions, decide to go around giving the PCs a round free from attacks.
6 – A wolf nips at the heels of one of the hooves of the horses. The driver needs to user their reaction to make a successful opportunity attack against it or the horse jostles the wagon as it kicks out at the wolf. Each PC has disadvantage on attack rolls made from the wagon this round.
7 – There’s a long slope up ahead. The driver need to make a Wisdom (Animal Handling) check vs DC10 to keep the horses at the right speed as the wagon is drawn upwards. Failure on this check keeps the speed but gives the horses a level of exhaustion.
8 – There’s a long downward slope up ahead that ends in a very sharp corner. The wagon travels at a dangerous speed, two wheeling around the corner. However, it manages to pull away from the wolves giving advantage on Stealth checks to escape them as the wagon pulls away.
9 – What fool left the low-hanging sign from the bridge struts? The road goes across a wooden bridge with a big “Slow Down, Bridge is Rickety” public service announcement at an incredibly inconvenient height. Any PCs stood in the wagon or on top of the carriage need to make a Dexterity save vs DC10 or suffer d6 bludgeoning damage and be knocked prone.
10 – Pot hole! The wagon’s wheel smashes into a whole clearly left by some poorly motivated highways engineer. The wagon is severely jostled and everyone aboard needs to make a DC15 Dexterity save or be knocked prone.
11 – 20 No hazard encountered.