Kuo-Toa Acolytes during the game's final sequence.
In order to summon him, the party must kill 
BOOOAL, which reveals him as a fake and frightens the Kuo-Toa into declaring the current party member "Mahkloompah", their new god.
Blood Frenzy (
)
The scent of blood sends the sahuagin into a 
Blood-scent Frenzy!
Blood-scent Frenzy grants the sahuagin 
Advantage on melee 
Attack rolls against any target that doesn't have all of its hit points, provided it's not a construct, an ooze, a plant or an elemental.
Range: 12 m / 40 ft
Recharge: Per turn 
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)
Melee: 1.5 m / 5 ft