Beluga

Deepsight: You have x-ray vision when underwater and darksight.

Spellcasting. The Beluga is a 5th-level spellcaster. Its spellcasting ability is Int (spell save DC 14, +3 to hit with spell attacks). The beluga has the spells prepared:
Cantrips (at will): Ray of Frost, Shape Water, and Shocking Grasp 
1st level (4 slots) : Create or Destroy Water, Ice Knife, Shield, Magic Missile, Shield of Faith, Snare, and Witch Bolt                                                                                                      2nd level (2 slots): Detect Thoughts, Invisibility, Mirror Image, and Web                            3rd level (2 slots): Fear, Lightning Arrow, Wall of Water, and Tidal Wave                                4th level (1 slot): Control Water, Ice Storm, and Watery Sphere                                               5th level (1 slot): Destructive Wave, Wall of Force, and Cone of Cold

Tail Swat

The beluga swats you with it's tail, dealing 4d10+2 damage on a failed saving throw. You must get 16 or above, without any modifiers.

Bellow 

This is an attack where the beluga bellows. It can reach up to a range of 275 feet, even if you are above water. If you hear it, you immeditaly take 1d4+3 damage and can not hear each other for one turn, meaning that you can not talk.

Underwater Current This is an attack where the beluga uses it's massive fins to throw an underwater wave at you. it can break the surface and reach up to 15 feet above the surface of the water. It has a range of 70 feet. If you are hit within20 feet, you take 3d8 +6 damage, and are pushed back 45 feet. If you are hit within 50 and 20 feet, you take 2d10+4 damage and are pushed back 15 feet. If you are hit within 70 and 50 feet, you take 2d6+2 damage, and are not pushed back at all. If you are hit in the air, this attack still hits you, but only does 1d4+2 damage. But if you are within 10 feet, you take 3d10+2 damage and will miss your next turn because you are stunned. 

Reaction Name. 

If someone enters the cave of the Beluga, the Beluga immediately attacks and deals 2d4+3 damage on a failed saving throw. You must get above a 13 for this to happen.

If the beluga is hit with an acid attack, it takes an extra 2d8 damage, because it spreads in the water. But if you are in the water as well when someone uses an acid attack, you take 2d4 damage even if it didn't hit you, because the acid spread to you

When the Beluga uses this action, he immediately destroys any boats in a 200 foot area in a rampaging frenzy.

Hull smash (Costs 2 Actions): Anyone and anything inside the boat takes 3d20 damage, and is plunged into the water. If you can not swim, then you take 4d10+8 damage for every minuite you take in the water, because you would drown.

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