Monster Mayhem Month 10

Greetings and Welcome to Monster Mayhem Month here at my blog. Everyday in October I will release a 4E Custom Monster of my design here!
Today the Monster is...

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Liquidform Elemental    Level 3 Soldier
Medium elemental magical beast (aquatic, water)    XP 150
HP 43; Bloodied 22
AC 19; Fortitude 15; Reflex 16; Will 14
Speed 6, swim 8
Resist 10 fire, 5 weapon; Vulnerability 5 lightning
Initiative +6
Perception +6
Darkvision
Traits
Threatening Reach
The elemental can make opportunity attacks against all enemies within its reach (2 squares).
Knock Down
When the Liquidform Elemental makes an Opportunity Attack , it get a +2 bonus to the attack roll and the target is Knocked Prone on a hit.
Standard Actions
m Liquidform Whip • At-Will
Attack: Reach 2; +8 vs. AC
Hit: 1d10 + 6.
Effect: Marked until the end of the Liquidform Elemental's next turn.
C Whiplash • Encounter
Attack: Close Burst 2 (Creatures in burst); +6 vs. Reflex
Hit: 1d10 + 6 damage and the target is knocked prone.
Triggered Actions
Liquidform Defence • Recharge first bloodied
Trigger: An attack is made against the Liquidform Elemental's AC or Reflex Defence.
Effect (Immediate Interrupt): The attacker rolls the attack twice and uses the lower result.
Skills Acrobatics +9, Athletics +8
Str 14 (+3)    Dex 17 (+4)    Wis 11 (+1)
Con 11 (+1)    Int 11 (+1)    Cha 11 (+1)
Alignment unaligned     Languages Primordial

© 2010 Wizards of the Coast LLC, a subsidiary of Hasbro, Inc. All rights reserved. This formatted statistics block has been generated using the D&D Adventure Tools.
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This Water Elemental, was an early experiment with Threatening Reach. I wanted it to be dangerous to get near it but hard to take down with common attacks. Also, this monster was made long before the Next playtest was even announced, so I had made "Disadvantage" before them too.