Boggle Trickster

Evasion. If the boggle is subjected to an effect that allows it to make a Dexterity saving throw to take only half damage, the boggle instead takes no damage if it succeeds on the saving throw, and only half damage if it fails.

Sneak Attack (1/Turn). The boggle deals an extra 14 (4d6) damage when it hits a target with a weapon attack and has advantage on the attack roll, or when the target is within 5 feet of an ally of the boggle that isn't incapacitated and the boggle doesn't have disadvantage on the attack roll.

Spellcasting. The boggle is a 7th-level spellcaster. Its spellcasting ability is Intelligence (spell save DC 11). It has the following wizard spells prepared:

Cantrips: infestation, mage hand, minor illusion

1st level (4 slots): disguise self, silent image, Tasha's hideous laughter

2nd level (2 slots): invisibility, phantasmal force

Uncanny Smell. The boggle has advantage on Wisdom (Perception) checks that rely on smell.

Dagger. Melee or Ranged Weapon Attack: +6 to hit, reach 5 ft. or range 20/60 ft., one target. Hit: 6 (1d4 + 4) piercing damage.

Oil Puddle. The boggle creates a puddle of oil that is either slippery or sticky (boggle’s choice). The puddle is 1 inch deep and covers the ground in the boggle’s space. The puddle is difficult terrain for all creatures except boggles and lasts for 1 hour.

If the oil is slippery, any creature that enters the puddle’s area or starts its turn there must succeed on a DC 11 Dexterity saving throw or fall prone.

If the oil is sticky, any creature that enters the puddle’s area or starts its turn there must succeed on a DC 11 Strength saving throw or be restrained. On its turn, a creature can use an action to try to extricate itself from the sticky puddle, ending the effect and moving into the nearest safe unoccupied space with a successful DC 11 Strength check.

Boggle Oil. The boggle excretes nonflammable oil from its pores. The boggle chooses whether the oil is slippery or sticky and can change the oil on its skin from one consistency to another as a bonus action.

 Slippery Oil: While coated in slippery oil, the boggle gains advantage on Dexterity (Acrobatics) checks made to escape bonds, squeeze through narrow spaces, and end grapples.

 Sticky Oil: While coated in sticky oil, the boggle gains advantage on Strength (Athletics) checks made to grapple and any ability check made to maintain a hold on another creature, a surface, or an object. The boggle can also climb difficult surfaces, including upside down on ceilings, without needing to make an ability check.

Cunning Action. On each of its turns, the boggle can use a bonus action to take the Dash, Disengage, or Hide action.

Dimensional Rift. As a bonus action, the boggle can create an invisible and immobile rift within an opening or frame it can see within 5 feet of it, provided that the space is no bigger than 10 feet on any side. The dimensional rift bridges the distance between that space and any point within 30 feet of it that the boggle can see or specify by distance and direction (such as "30 feet straight up"). While next to the rift, the boggle can see through it and is considered to be next to the destination as well, and anything the boggle puts through the rift (including a portion of its body) emerges at the destination. Only the boggle can use the rift, and it lasts until the end of the boggle's next turn.