Encounter 10 - lvl 5 to 10

2x Chuul Large aberration , chaotic evil
Armor Class 16 (Natural Armor) Hit Points (11d10 + 33) Speed 30 ft., swim 30 ft.
STR 19 (+4) DEX 10 (+0) CON 16 (+3) INT 5 (-3) WIS 11 (+0) CHA 5 (-3)
Skills Perception +4 Damage Immunities Poison Condition Immunities Poisoned Senses Darkvision 60 ft., Passive Perception 14 Languages Understands Deep Speech but can't speak Challenge 4 (1,100 XP) Proficiency Bonus +2
Amphibious. The chuul can breathe air and water.
Sense Magic. The chuul senses magic within 120 feet of it at will. This trait otherwise works like the detect magic spell but isn't itself magical.
Enrage. The chuul will Enrage after 3/8th of its Health is depleted. This will grant the chuul the ability to roll a DC 13 CON save to shrug off magical damage. The effect is dispelled when the chuul succeeds the save.
Actions Multiattack. The chuul makes two pincer attacks. If the chuul is grappling a creature, the chuul can also use its tentacles once.
Pincer. Melee Weapon Attack: +6 to hit, reach 10 ft., one target. Hit: (2d6 + 4) bludgeoning damage. The target is grappled (escape DC 14) if it is a Large or smaller creature and the chuul doesn't have two other creatures grappled.
Tentacles. One creature grappled by the chuul must succeed on a DC 13 Constitution saving throw or be poisoned for 1 minute. Until this poison ends, the target is paralyzed. The target can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success.