Amphicoelias (5e Creature)
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Gargantuan beast (sauropod), unaligned
Saving Throws Str +19, Con +19, Wis +12
Thick Skin. If an attack deals less than 50 damage to the amphicoelias the damage is reduced to 5 (before resistances).
Multiattack. The amphicoelias makes two attacks: one with its stomp and one with its tail.
Stomp. Melee Weapon Attack: +19 to hit, reach 10 ft., one target. Hit: 175 (30d10 + 10) bludgeoning damage. If target is a creature, it must succeed on a DC 24 Strength saving throw or be knocked prone. If the creature is already prone any hit with this attack counts as a critical hit.
Tail. Melee Weapon Attack: +19 to hit, reach 40 ft., one target. Hit: 98 (16d10 + 10) bludgeoning damage, and each creature within 30 feet of the ampicoelias must succeed on a DC 20 Constitution saving throw or take 15 (3d10) thunder damage and be deafened for 1 minute. An affected creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success.
The amphicoelias is a sauropod shrouded in legend. There are said to be a herd somewhere in the dense Chuult rainforest. These creatures are the largest land animal people may see. The largest adult killed was 155 feet long, some say they have seen larger. These creatures act like mobile ecosystems and some argue sapient.