Traits

Echolocation: The Deafened rendered this killer whale unable use its blindsight during the day.

Keep your breath.This whale can hold its breath for up to 30 minutes

Keen Hearing: The killer whale is able to rely on its wisdom (Perception) checks.

Actions

Bite: The dnd 5e killer whale monster is able to use a bite attack attack. It can also make a Melee Weapon attack: +6 to hit, reach five feet, and one target. Hit: 21 (5d6 + 4), piercing damage.

Killer Whale Monster DnD 5E: Attributes

AC 12 (Natural Armor).
Alignment Unaligned
CHA 7
CON 13
Challenge Rating 3
DEX 10
HP 90 (12d12+12)
INT 3
Passive Perception 13
STR 19
Senses Blindsight 120 ft.
Size Huge
Skills Perception +3
Speed Swim 60 ft.
Type The beast
WIS 12