Amorphous. The Globglogabgalab can move through a space as narrow as 1 inch wide without squeezing.
Shapechanger. As a bonus action, the Globglogabgalab can change its shape to resemble the shape of a creature that it has seen. It retains all of its statistics and abilities, except for its size and speed (including flying and climbing speed), which change to match those of the selected creature.
Spellcasting. The Globglogabgalab is a 12th·level spellcaster. Its spellcasting ability is Intelligence (spell save DC 18, +10 to hit with spell attacks). It requires no material components to cast its spells. The Globglogabgalab has the following wizard spells prepared:
Cantrips (at will): mage hand, poison spray, prestidigitation
1st level (4 slots): command, cause fear, absorb elements
2nd level (3 slots): detect thoughts, zone of truth, crown of madness
3rd level (3 slots) : clairvoyance, counterspell, fear, lightning bolt
4th level (3 slots): confusion, vitriolic sphere
5th level (2 slots): legend lore, animate objects, synaptic static
6th level (1 slot): eyebite
Multiattack. The Globglogabgalab makes two melee attacks. if Sing is ready, it can use it instead of one of the attacks.
Slam. Melee Weapon Attack: +10 to hit, reach 10 ft., one target. Hit: 9 (1d10 + 4) bludgeoning damage, plus 5 (1d10) acid damage.
Extend (Recharge 5-6). The Globglogabgalab extends itself into a line 10 ft. wide and 100 ft. long, slamming into all creatures in the line. Every affected creature must make a DC 18 Dexterity saving throw, taking 44 (8d10) damage and falling prone on a failed saving throw. On a successful save, a creature takes half as much damage and doesn't fall prone.
Sing (1/Day). Each creature within 120 ft. of the Globglogabgalab that fails a DC 18 Wisdom saving
throw is frightened for 1 minute. A frightened creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success .
The Globglogabgalab can take 3 legendary actions, choosing from the options below. Only one legendary action option can be used at a time and only at the end of another creature's turn. The Globglogabgalab regains spent legendary actions at the start of its turn.
Melee Attack. The Globglogabgalab makes a melee attack.
Book Shift (Costs 2 Actions). If it is within 5 ft. of a book, The Globglogabgalab teleports to a location within 5 ft. of a different book that is within 100ft. of his original location, and regains 1d12 hit points.
Cast a Spell (Costs 3 Actions). The Globglogabgalab casts a spell from its list of prepared spells, using a spell slot as normal.