Bloated, Spindle Legged Giant

Exposed Legs: Small or Medium creatures can move into the Giant space (the 8 outside squares surrounding its spindly legs). From this position melee attacks against the Giant have advantage and the Giants AC is reduced by 5.

Large or larger creatures can only attack the Giant normally. 

Ranged attacks can only target the legs from within 10 ft of the Giant, and these attacks are always made at disadvantage. Outside 10 ft (outside the Giants threat range), ranged attacks are made normally.

Limited Threat/Reach: The Giant does not threaten the eight squares surrounding its legs, as he cannot see or attack smaller creatures under his belly. However, this also means that moving from standard melee under his legs creates an attack of opportunity. 

Deep Plie: Move action. During its turn, it may perform a Deep Plie -- that is quickly and forcefully drop the bulk of its midsection to the ground, and return to his standing position.  Each creature standing under the Giant (Exposed Leg positions) must make a DC 18 STR saving throw.  On a failure, the creature is pushed back 10 ft and knocked prone.  Each creature that saves takes 2d10+7 bludgeoning damage and the giant takes half of all the damage dealt to others in this way.

Attack Action: The Giant can make 2 Spear attacks as an attack action

Action Melee Attack. Giant Curved Spear: +9 to hit, reach 10 ft., 1 target. Hit: 20 (3d8 + 7) [piercing] damage. 

Free Attacks of Opportunity: Despite its bulk, the Giant is dexterous and quick. He can use an attack of opportunity twice on each creatures turn.. but only one attack on any given creature per turn. Also, disengaging does not affect his ability to make opportunity attacks.