Basin Sea Reaper

Standby. The Basin Sea Reaper begins combat without moving or using the attack action on its turn. 

Combat-Ready. When the Basin Sea Reaper is attacked it enters a state where it can attack and move as normal. When in this state the Basin Sea Reaper loses 10% of its max hit points at the end of its turn,  also gaining +1 to attack rolls and damage for every 20% of max hit points it is missing (max +4).

Frenzied Incision. If on the Basin Sea Reaper's atttack action it hits its first claw attack, its second attack will apply an extra (1d4) Poison damage and double the applied Nervous Impairment if the target fails the claw attack saving throw. If the Basin Sea Reaper hits its first claw attack and instead misses the second claw attack the attack will still go through but instead dealing the smallest damage number possible to be rolled and will instead apply half the Nervous Impairment.

Abyssal Horror. When the Basin Sea Reaper is at 50% of its maximum hit points or lower and misses an attack the attack will still go through but instead dealing the smallest damage number possible to be rolled and will instead apply half the Nervous Impairment.

Nervous Impairment. At 30 stacks of this effect the creature loses all stacks of Nervous Impairment and becomes paralyzed until the end of their next turn.The creature also rolls their hit dice, taking poison damage equal to 1/4 of the number rolled. At the end of a creature inflicted with any stack of Nervous Impairment's turn the stack goes down by one. If a stack of Nervous Impairment has not been applied within 1 minute the effect dissipates.

Nethersea Brand Utopia. When the Basin Sea Reaper is on top of Nethersea Brand it gains advantage on attack rolls and applies double the Nervous Impairment.