Luke drew his lightsaber as well, moving closer. He did remember all too clearly the fight at Jabba's, but later experiences had left him with a more nuanced view of these creatures. They were at least semi-sentient and were tamed by the Dathomiri witches, who rode atop the great beasts. One even attempted to learn to read and write so she could teach others. However, Luke wasn't holding out much hope about this one. He was alert for anything, and tried to send feelings of calmness and not meaning harm through the Force, but he wasn't sure that whatever was behind this hadn't brought an altered one, one that wouldn't respond to him. He was prepared to fight if need be.
He saw the newcomer zap the rancor, and that probably wouldn't help things.
"I've fought one of these before. Be careful." he said, readying himself.