Armored Undead Ogre Boss

Second phase. If the Ogre is reduced to half its starting hit points, a shockwave is released, throwing anyone within 30ft of the Ogre 10ft away from the Ogre and taking 1d6 shock damage. The Ogre takes on a more monstrous form as metal spikes shoot out from along it's spine and arms. In the second phase, the Ogre gains the following traits:

• Spiked Hell. Any character entering or ending its turn within 5ft of the Ogre takes 1d4 piercing damage
• Spiked Reflection. Any character attacking the Ogre with a melee attack with a range of 5ft take 1d6 piercing damage

The Ogre can use 2 of these attacks each turn:

Heavy slam. Melee Weapon Attack: +7 to hit, reach 5 ft., 1 target. Hit: 13 (2d8 + 5) bludgeoning damage. 

Bite. Melee Weapon Attack: +7 to hit, reach 5 ft., 1 target. Hit: 11 (1d6 + 5) piercing damage. The target must succeed a DC14 constitution save or become poisoned for 1 round.

Throw. If any suitable heavy rocks or other similarly heavy items that can be picked up is within 5ft of the Ogre, it can pick it up and throw it with a range of 30ft. The target must succeed a DC12 acrobatics saving throw or suffer 15 (3d10) damage.

Knock Back. The Ogre can as a bonus action knock 1 target 5ft. away (causes no damage)

Monstrous Slam. The Ogre uses its large slabs of armor to smash the attacker, causing 1d8 damage. The attacked must succeed a DC14 Athletics check or be flung 5ft back and knocked prone.

Massive Slam (Costs 2 Actions). The Ogre slams the ground with all its might and any character within 40ft of the Ogre takes 2d10 shock damage and must make a DC16 athletics save. On a failed save the target is stunned until the end of its next turn. On a successful save, the damage is halved and the target is knocked prone instead of stunned.