I wanted to try and design a creature I could use for my campaign

The Leviath are a race of deadly, calculating, amphibian humanoids who are notorious for their agility, and maneuverability. They often ambush adventurers or grave robbers by hiding behind pillars or ducking behind fence, and when their victim gets close, snap! they lash at them through crevices and around corners using their snake like heads.
This tactic used in groups, and their regenerative abilities has earned them the name Leviath, which is derived from Leviathan (if you couldn't tell <-> )