Okay, so the party is in a jungle, with Jabba's animal master (Malakili) holding a baby rancor, and they're about to be chased by an adult rancor who hears the baby's cries. The adult rancor may also be radioactive and/or on fire.

4 members of the party (plus Malakili & baby) are on foot, without weapons that can do much damage to the rancor, and 2 are in a weaponless ship that shot off a ways away after the pilot opened up the after-burners in-atmosphere on the rancor's face to make the rancor leave the planet-bound party alone (hence why it might be on fire). The "radioactive" part is probably just fluff, since there's a crashed ship reactor core nearby that's been leaking into the environment.

So how would you guys run a challenge like this to give it a Jurassic Park, running from the monster sort of feel? It's a widely varied party, so they don't all have the skills that might make sense to use (like Athletics). I don't want to kill them, but I want it to be as dramatic & memorable as possible.

Oh, and there's also the possibility of Malakili & the baby being slower, and the chance that they might repair a repulsor sled (speed undetermined) that they had initially planned to put the rancor egg on.

Your wisdom is appreciated.

Pg 239. Chase mechanics. Replace the Rancor's Piloting check with Athletics. Thing has a high enough brawn that it should be able to keep up long enough to make it interesting. If it's still chasing after about turn 4 or 5 require the rancor to roll increasingly difficult resilience checks each round starting at hard and going up each round. When it finally fails, it's just too tired to keep up.

****, what a set up! My hat's off to you, sir.

Like Ghost said above, the chase mechanics can easily be adapted to foot speeds. Other options might include hiding (Boost dice to anyone who uses mud or other natural camouflage to mask their scent) and maneuvering such that the rancor would struggle to follow, i.e. through thickets, rivers, etc.

Dice-wise, have everyone roll an Athletics check, probably opposed to the rancor's. Anyone who fails has to deal with being within arm's reach of the rancor (basically, weather an attack attempt). Threat gives the rancor Boost dice, Advantage gives the rancor Setback dice. Despair and Triumph should probably be situational. Roll for Malakili as well, and assuming he fails, you could allow a player to get between him and the rancor, essentially taking his attack.

Honestly, though, I think a straight chase would be dramatic enough. Maybe the sneakiest player could try to hide Malakili and the baby, but unless they can pacify the cub/grub/whatever, the rancor will probably be able to find them anyway.