Boneslime

Undead ooze : The Boneslime is treated as both an undead and an ooze.

Necrotic and Acid Healing: Both necrotic and acid damage heal the boneslime instead of damaging it.

Demonic ooze: The body of the creatures in made mainly of demonic ooze, which is an highly corrosive material capable of dissolving everything that comes in contact with it. Given enough time, the Boneslime acid can destroy any material, the only exceptions are the bones of the creatures used to construct the "skeleton" of the monster, and the bones it uses as weapon in its claws and bone splinter attacks.

Corrosive gelatinous body: All enemies that physically attack  the Boneslime might get their weapon stuck inside the ooze, unless they pass a Strength/Dexterity check (DC:13). In case of failure the weapon is stuck and  the creature can't make any further attacks with that weapon. The check can be repeated  if the creature has any actions left, or at the start of his own turn. If the check is failed 2 other times the object is completely engulfed inside the monster and the creature must enter the corrosive body to recover it. If the object is not retrived after being engulfed will be destroyed in 1d4 +1 rounds.

The Bonelime can perform 3 attacks per round or use one of the following abilities  instead of an attack

Slam. The Boneslime uses his limbs to smash one creature in its reach .Melee Weapon Attack: +7 to hit, reach 10 ft., one target. Hit: 9 (2d6 + 4)  bludgeoning damage. 

Claw. Sharps bone pieces protudes from the limbs of the Boneslime and are used to slash deep cuts into opponents flesh. Melee Weapon Attack: +7 to hit, reach 10 ft., one target. Hit: 9 (2d6 + 4)  slashing damage. 

Bone Splinters. The Boneslime can exlploit unused bones inside his body to expell sharp bone splinter around himself in a radius of 10 ft damaging all enemies around him with peircing damage for (2d6+4 damage) unless the creatures surrounding him pass a DC: 13 dexterity/constitution check to dodge/withstand the attack, in the first case the creature take no damage, in the second case half the damage.  (Recharge 5-6)

Engulf: If the boneslime hit a creature with a melee attack it will apply the normal damage of the attacks and can choose to spend one additional attack to engulf the hit creature inside its body. The engulfed creature is considered restrained and starts suffocating. The Boneslime can engulf only one medium sized creature at a time. The restrained can break free by passing a Strength check (DC:13) or if another creature from the outside attacks the monster and inflicts at least 15 points of damage in the same round, breaking the layer of slime between the restrained and the outside. The engulfed creature takes 3d6 acidi damage at the start of the boneslime turn, and if it drops at 0 hp with this damage is completely dissolved and assimilated into the Boneslime body, healing it by the amout of the damage done in this way.

Split: If the Boneslime takes enough damage in one round (at least 1/4 of his hp) (42) it will detach part of its body producing medium sized slime, with 1/4 of its remaining hp and half his damage (eg: 2d6+4 will become 1d6+2). The only action possible for this smaller slime will be regular physical attacks and no other special abilities of the Boneslime. (recharge 5-6)