Blue Whale (5e Creature)
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Gargantuan beast, unaligned
Echolocation. The whale can't use its blindsight while deafened.
Keen Hearing. The whale has advantage on Wisdom (Perception) checks that rely on hearing.
Massive Lungs. The whale can hold its breath for 90 minutes. The whale won't lose his held breath as a result of damage.
Extremely Heavy. The whale can survive for 3 hours on land. Every turn thereafter, the whale takes 1 bludgeoning damage for every turn it remains on land. This damage comes from its weight crushing it, so being magically lifted, being given a flying speed, or other means of the DM's discretion can prevent it. Additionally, the whale takes twice as much damage from falling, but if it falls onto a creature, that creature takes an equal amount of bludgeoning damage.
Bristled Chomp. Melee Weapon Attack: +12 to hit, reach 10 ft., one target. Hit: 62 (10d10 + 7) bludgeoning damage. If the target hit is a large or smaller creature, the creature is grappled (escape DC 21). While the creature is grappled this way, it is restrained. The whale can grapple 4 Large creatures, 16 Medium or Small creatures, or 1000 Tiny creatures this way.
Swallow. The whale makes on Bristled Chomp against all creatures it has grappled in its mouth. If the attack hits a Tiny size creature, the creature is also swallowed, and the grapple ends. While swallowed, the target is blinded and restrained, it has total cover against attacks and other effects outside the whale, and it takes 21 (6d6) acid damage at the start of each of the whale's turns. A whale can have any number of Tiny creatures swallowed at once. If the whale takes 30 damage or more on a single turn from the swallowed creatures, the whale must succeed on a DC 16 Constitution saving throw at the end of that turn or regurgitate all swallowed creatures, which fall prone in a space within 30 feet of the whale. If the whale dies, a swallowed creature is no longer restrained by it and can escape from the corpse by using 60 feet of movement, exiting prone.
With the largest known examples being over 98 ft. long and 196 tons heavy, blue whales are thought to be the largest animals to have ever existed in the real world. They are filter feeders, with baleen plates; long, bristle-like keratin constructs in their mouths filtering microscopic prey, primarily krill, from the water around them. Due to this diet, there is no necessity for a large digestive tract, making it impossible for them to swallow larger creatures.
Mythical Blue Whale Variant. Due to their size, blue whales have been revered and feared in the past, with myths of ship-swallowers that could shake islands with their large fins, gaining the following:
Mythic Weakness. Releasing pepper in the mouth of the whale forces it to open its mouth and release every creature grappled by it.
Enhanced Swallow. If the Bristle Chomp from the whale's Swallow action hits any creature, they become swallowed. A whale can have up to 4 Large creatures, 16 Medium or Small creatures, or 1000 Tiny creatures swallowed at once. These creatures take 36 (8d8) acid damage at the start of each of the whale's turns.