Arthro Chitinfolk

Amphibious. Arthro Chitinfolk can breathe air and water. 

Powerful build. Arthro Chitinfolk count as a size larger when determining its carrying capacity and the weight it can push, drag or lift. 

Sentinel. When the Arthro Chitinfolk hits a target with an attack of opportunity the target's speed becomes 0 until its next turn. Creatures who Disengage from Arthro Chitinfolk also provoke attacks of opportunity and when a creature within 5 ft of an Arthro Chitinfolk makes an attack against a different target it can use its reaction to make one attack against it. 

Spellcasting. The Arthro Chitinfolk has following spells prepared:

At will: Create or Destroy Water
(1/day): Move Earth

Multiattack. Arthro Chitinfolk make two attacks.

Cleaver. Melee Weapon Attack: +7 to hit, reach 10 ft., 1 target. Hit: 18 (2d12 + 5) slashing damage. 

Claw. Melee Weapon Attack: +7 to hit, reach 5 ft., 1 target. Hit: 12 (1d10 + 5) bludgeoning damage. A target must make a strength saving throw (DC 15) or is grappled by the Arthro Chitinfolk. 

Reflex Strike. When a creature hits the Arthro Chitinfolk with a melee attack, it can make one Cleaver attack against it. 

Defensive Nature. If a creature makes an attack against an Arthro Chitinfolk, they can attempt to block the incoming attack. Roll a d6 and add the total to the Arthto Chitinfolk's AC.