Chaos Ape

Chaos Incarnate. Chaos Apes are innately tapped into the chaos of the universe. Due to this all interactions with them can be wildly unpredictable. ALL interactions that require a d20 roll also require chaos rolls by the DM or player as stated below:

Non-combat interactions. After all interactions that require d20 skills checks, the player rolls a d6. On a 1-3 - skill check roll result stands as rolled. On a 4-6 - skill check roll result is reversed

Combat interactions. After all attack rolls against chaos Apes, the DM rolls a d6. If the attack roll was successful the following applies: On a 1-2 - attack roll remains as rolled, on a 3-4 - attack roll fails, on a 5 - attack damage is doubled against chaos ape, 6 - damage is transferred to an ally of attacker as determined by a roll by DM

Multiattack. The chaos ape makes two random weapon attacks.  At beginning of attack, DM rolls a d6 and a weapon appears in the chaos ape's hand based on the following: On a 1-2 - a greatsword appears, on a 3-4 - a greataxe appears, on a 5-6 - nothing appears and the chaos ape uses its fists (2 hits per attack) The chaos ape is proficient in the use of the weapon.

Random Weapon. Melee Weapon Attack: +15 to hit, reach 10 ft., one target. Hit: 22 (1d12 + 15) bludgeoning damage or Hit: 23 (2d6 + 15) slashing damage or Hit: 22 (1d12 + 15) slashing damage

Call the Troop. After d6 rounds, and only 1/combat, a chaos ape can call out to its troop members across the multiverse. DM rolls a d6 and a certain number of chaos apes will appear based on the following: On a 1 - 0 apes appear, on a 2-4 - 1 ape appears,  on a 5-6 - 2 apes appear. All called chaos apes make an initiative roll upon arrival. Called chaos apes can not use this feature for d6 rounds.

Resistance Gamble. Once per turn as a reaction to an attack that hits, a chaos ape reacts to the damage type of the attack as per a d6 roll by the DM as follows: On a 1-2 - the chaos ape is affected normally, on a 3-4 - the chaos ape is resistant, on a 5 - the chaos ape is immune, on a 6 - the chaos monkey is vulnerable

Death means something?  When a chaos ape is reduced to 0 hit points, the DM rolls a d6 and the following applies: On a 1-3 - the chaos ape dies, on 4-6 - the chaos ape's chaos energy explodes. All creatures within 60 ft must make a DC 22 DEX save and take 4d10 force damage upon a failure or half as much on a success