Sources
CR
Type
Size
Alignment
Movement

Water Elemental Myrmidon

Medium Elemental, Neutral

Armor Class 18 (plate)
Hit Points 127 (17d8 + 51)
Speed 40 ft., swim 40 ft.
STR
18
+4
DEX
14
+2
CON
16
+3
INT
8
-1
WIS
10
+0
CHA
10
+0
Damage Resistances acid; bludgeoning, piercing, slashing, from nonmagical attacks
Damage Immunities poison
Condition Immunities Paralyzed, Petrified, Poisoned, Prone
Senses darkvision 60 ft., passive Perception 10
Languages Aquan, one language of its creator's choice
Challenge 7 (2,900 XP)

Actions

Multiattack. The myrmidon makes three Trident attacks.

Trident. Melee or Ranged Weapon Attack: +7 to hit, reach 5 ft. or range 20/60 ft., one target. Hit:7 (1d6 + 4) force damage, or 8 (1d8 + 4) force damage if used with two hands to make a melee attack.

Freezing Strikes (Recharge). The myrmidon uses Multiattack. Each attack that hits deals an extra 5 (1d10) cold damage. A target that is hit by one or more of these attacks has its speed reduced by 10 feet until the end of the myrmidon's next turn.

Lore

Elemental myrmidons are Elementals conjured and bound by magic into ritually created suits of plate armor. In this form, they possess no recollection of their former existence as free Elementals. They exist only to follow the commands of their creators.