Valley of the Brain Collectors as a sandbox had plenty of optional encounters. However my players are very focused, it didn’t make sense to their practical hearted characters to disturb every nest in the Scar of the Spider. They stayed on mission. So they actually minimised and avoided contact with the inhabitants totally skipping the Cthulhu Mythos inhabited Fungal Cave. Here is the Gug with the Pathfinder original here.
Armor Class 18 (natural armor)
Hit Points 170 (20d8 + 80)
Speed 40 ft., climb 20 ft.
STR 20 (+5) DEX 15 (+2) CON 19 (+4)
INT 10 (+0) WIS 10 (+0) CHA 11 (+0)
Skills Perception +8
Damage Immunities disease, poison
Senses blindsight 60 ft., darkvision 60ft., passive Perception 18
Challenge 10 (5,900 XP)
Compression. A gug can contort and distend its limbs for greater reach or to wriggle easily through impossibly Small passages.
Magic Resistance. The gug has advantage on saving throws against spells and other magical effects.
Magic Weapons. The gug’s weapon attacks are magical.
Regeneration. The gug regains 10 hit points at the start of its turn if it has at least 1 hit point.
Multiattack. The gug makes three attacks: one with its bite and two with its claws.
Bite. Melee Weapon Attack: +9 to hit, reach 15 ft., one target.
Hit: 9 (ld8 + 5) piercing damage plus 7 (2d6) psychic damage.
Claws. Melee Weapon Attack: +9 to hit, reach 15 ft., one target.
Hit: 10 (ld10 + 5) slashing damage plus 7 (2d6) psychic damage.
This towering menace has a horrible, vertically aligned mouth and arms that split at the elbows into twin clawed hands.