They aren’t terribly bright, but they’re pretty tough with a 16 and 15 in Strength and Constitution respectively. This means that if you kill one and grind up its gizzard into a raw patty, and then feed it to the petrification victim, you should be able to cure them.
So a basalisk is CR 3 and is the 'boss' so you are looking at CR 2 encounters and below for the dungeon.
