Shimmerfish (5e Creature)
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Medium monstrosity, chaotic evil
Charge. If the shimmerfish moves at least 30 feet straight toward a target and then hits it with a bite attack on the same turn, the target takes an extra 3 (1d6) piercing damage.
Hold Breath. The shimmerfish can hold its breath for 20 minutes.
Shimmering Illusion. The shimmerfish can form rough, shimmering images underwater with its body, appearing like a sunken treasure or a luminescent humanoid form to lure prey. A creature that sees the shimmering images can tell they are an illusion with a successful DC 13 Wisdom (Insight) check.
Bite. Melee Weapon Attack: +4 to hit, reach 5 ft., one target. Hit: 6 (1d6 + 3) piercing damage.
Shimmerfish are deadly, evil relatives of the friendly dolphin. These sleek and powerful swimmers are found in warm seas. Shimmerfish, unlike dolphins, are never found in fresh water. Both dolphins and shimmerfish often appear in open waters, making their characteristic arched bounds, frequently before the bow waves of ships. They have the ability to make glowing images with their bodies to lure unsuspecting sailors and swimmers. Once the victim is in reach the shimmerfish will bite viciously with their razor sharp teeth. Shimmerfish love to prolong a victim's death, teasing, drawing out the terror. Shimmerfish sometimes "rescue" victims of a shipwreck, carry them heartbreakingly close to shore, and then attack, just to watch the victims' rising hopes come crashing down in a rising tide of desperation.
Shimmerfish follow schools of fish in groups of varying size. Most groups contain only a few members, although occasionally larger groups will form temporarily. In one day, a shimmerfish eats nearly one-third of its weight, mostly in fish and squid.
Shimmerfish have a language composed primarily of clicking sounds and whistles. These also act as part of an echolocation system, similar to that of a bat, enabling the shimmerfish to navigate and detect prey.
Shimmerfish have a gland in the head that holds a small quantity of valuable oil, which is used to lubricate delicate mechanisms. Each shimmerfish gland holds about one ounce of oil, which sells for between one and five gold pieces. Also, raw, uncured hide sells for about two gold pieces, and a cured shimmerfish hide is a beautiful thing worth at least 10 gold pieces.