D&D 5E Spellweaver moster stats for 5e?

[Tormyr]

This is the spellweaver lich I made for my Age of Worms campaign. It can cast up to 6 levels of spells per round (or 1 spell higher than 6th level). It can also burn legendary actions to cast levels of reaction spells. Thankfully the party just talked instead of doing its usual thing of picking a fight. Its opening would have been 2 fireballs. He can reliably boost his AC with shield and will win a counterspell duel, but it will cost lots of spell slots quickly. This one is obviously too powerful for your party, but you get the general idea.

Mak’ar
Medium undead, chaotic evil
Armor Class 15 (18 with mage armor)
Hit Points 97 (13d8 + 39)
Speed 30 ft.
STR DEX CON INT WIS CHA
8 (-1) 18 (+4) 16 (+3) 20 (+5) 14 (+2) 16 (+3)
Saving Throws Str +0, Dex +5, Con +10, Int +12, Wis +9, Cha +4
Skills Arcana +16, History +11, Insight +8, Perception +8
Damage Resistances cold, lightning, necrotic
Damage Immunities poison; bludgeoning, piercing, and
slashing from nonmagical weapons
Condition Immunities charmed, exhaustion, frightened,
paralyzed, poisoned
Senses truesight 120 ft., passive Perception 18
Languages Telepathy 1,000 miles
Challenge 17 (200 XP)
Special Equipment. Mak’ar has a cloak of protection.
Spell Weaving. Mak’ar can cast multiple spells during his turn
as long as the spell levels add up to 6 or fewer. He can only cast
one spell if its level is 6 or higher. Cantrips count as a 1st-level
spell for this purpose. Mak’ar can also concentrate on multiple
spells as long as the spell levels add up to 6 or fewer. He can
only concentrate on one spell if its level is 6 or higher. Mak’ar
can choose one or more spells to stop concentrating on if a new
concentration spell is cast that would put him over his limit.
When Mak’ar must make Concentration saving throws, he
makes a Concentration saving throw with advantage for each
spell that he is maintaining concentration.
Legendary Resistance (3/Day). If Mak’ar fails a saving throw,
he can choose to succeed instead.
Spellcasting. Mak’ar is a 16th-level spellcaster. Its spellcasting
ability is Intelligence (spell save DC 19, +11 to hit with spell
attacks). Mak’ar has the following wizard spells prepared:
Cantrips (at will):
1st level (4 slots): expeditious retreat, false life, mage armor,
magic missile, protection from evil and good, shield
2nd level (3 slots): blur, mirror image, ray of enfeeblement,
scorching ray
3rd level (3 slots): counterspell, dispel magic, fireball, slow,
vampiric touch
4th level (3 slots): confusion, fire shield
5th level (3 slots): cone of cold, contact other plane, hold
monster, wall of force
6th level (1 slot): chain lightning
7th level (1 slot): prismatic spray
8th level (1 slot): dominate monster, maze, power word stun
Turn Resistance. Mak’ar has advantage on saving throws
against any effect that turns undead.
Actions
Paralyzing Touch. Melee Spell Attack: +11 to hit, reach 5 ft.,
one creature. Hit: 10 (3d6) cold damage. The target must
succeed on a DC 18 Constitution saving throw or be paralyzed
for 1 minute. The target can repeat the saving throw at the end
of each of its turns, ending the effect on itself on a success.
Legendary Actions
The Mak’ar can take 6 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 (except
when taking a spell reaction). The Mak’ar regains spent
legendary actions at the start of its turn.
Spell Reaction (Cost Varies). The Mak’ar casts a spell with a
casting time of a reaction. The number of actions is equal to the
level of the spell. Mak’ar may take more than one Spell
Reaction per round.
Cantrip. The Mak’ar casts a cantrip.
Paralyzing Touch (Costs 2 Actions). The Mak’ar uses its
Paralyzing Touch.
Frightening Gaze (Costs 2 Actions). As per the lich (MM 202).
Disrupt Life (Costs 3 Actions). As per the lich (MM 202).

 

[Njalm2]

My Version of the Spellweaver for 5e

Alright, I recently made a Spellweaver of my own inspired by both the Second and Third edition versions of the monster, given the excellent work done thus far in this thread, I decided to incorporate these ideas into the final design I had for the creature. Its stats are based off of its third edition incarnation, and although it does look squishy and easily killable, a look at its spell selection should give you an idea that it probably isn't. Due to its ability to turn invisible at will, and teleport more or less as it pleases, it should almost always be able to ambush the party. While protecting itself with every single protective spell in its arsenal.

Now, I went ahead and made it a legendary creature based on the fact that they're almost encountered on their own, and are supposedly beings of great power. Besides, encountering more of these things would be a nightmare for most players, and DMs, as they're fairly complicated to run I think.

Credit goes to Dave for his significant contribution! It'd have turned out less interesting without his succinct stat block.
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Spellweaver
Medium monstrous humanoid, neutral, legendary
Armor Class 18
Hit Points 45 (10d10 -10)
Speed 30 feet.

STR 9 (-1), DEX 16 (+3), CON 9 (-1), INT 18 (+4), WIS 17 (+3), CHA 16 (+3)

Saving Throws Dex +8, Int +9, Wis +8
Skills Arcana +13, Perception +8
Damage Resistances psychic; bludgeoning, piercing, and slashing that is nonmagical
Condition Immunities charmed, frightened
Senses detect invisibility 100 ft., passive Perception 18, detect magic
Languages -, telepathy 120 ft., see also telepathic bond
Challenge 10 (5,900 XP)

Chromatic Disk. Spellweavers carry a 6-inch disk of an unknown and nearly indestructible material. The disk stores magical energy, containing up to 10 sorcery points that the spellweaver can use as a bonus action. Once the spell points are used, they are gone. However, the disk can be recharged by absorbing magic. The disk gains one sorcery point for each level of the spell it absorbs, up to its sorcery point maximum of 10. Refer to magic resistance.

The Spellweaver's spellcasting ability is Intelligence (spell save DC 16). It can innately cast the following Spells, requiring no material components:

Always Active: Detect Invisibility
At will: Detect Magic, Invisibility
1/day: Plane Shift

Magic Resistance. The spellweaver has advantage on all saving throws against spells. In addition, if the spellweaver succeeds on its saving throw it may use its reaction to capture the spell in its chromatic disk. The spellweaver suffers no damage or effect from a spell it has absorbed with its chromatic disk.

Metamagic. The spellweaver has 12 sorcery points and knows the distant spell and empowered spell metamagic abilities. It can convert spell slots and sorcery points in the same manner as a sorcerer.

Shielded Mind. Attempts to communicate telepathically with the spellweaver, or to read its mind, always fail. A creature making an attempt must succeed on a DC 14 Wisdom saving throw or be affected by a confusion spell.

Spellcasting: the Spellweaver casts spells like an 11th-level wizard. Its spellcasting ability is Intelligence (spell save DC 16, to hit with spell attacks +8). Refer to the spell points trait for its number of spells per day.

Cantrips (at will): Ray of Frost, Prestidigitation, Acid Splash, Mage Hand, Dancing Lights, Minor Illusion
1st level: Magic Missile, Thunderwave, Shield, Charm Person
2nd level: Melf's Acid Arrow, Hold Person, Misty Step, Mirror Image
3rd level: Fly, Counterspell, Blink, Fireball
4th level: Greater Invisibility, Ice Storm, Stoneskin, Dimension Door
5th level: Cone of Cold, Teleport, Cloudkill, Mislead
6th level: Circle of Death, Disintegrate, Contingency

Spellweaving. Each spell level cast takes one hand. (A third level spell costs three hands, a fourth costs 4, etc.) The Spellweaver may cast as many spell levels as he has hands, in any combination. It must pay the spell point cost for each spell cast, but may not exceed 6th level. Cantrips take up one hand. In addition, a spellweaver can concentrate on up to two spells at a time and only one spell is interrupted each time it fails a concentration check. It also gets two reactions between each of its turns.

Spell Points: A spell weaver has a number of “spell points” (one point for each spell level) equal to its hit points. It can use each spell in its arsenal any number of times within the limit of its spell-point total. Increasing the strength of its spells requires an investment of additional spell points and arms as neccessary.

ACTIONS:

Multiattack. The spellweaver can make up to six slam attacks.

Slam. Melee weapon attack: +8 to hit, rech 5 ft., one target. Hit: 2 (1d4) bludgeoning damage.

LEGENDARY ACTIONS: The Spellweaver can take 2 legendary actions, chosen 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. It regains its spent legendary actions at the start of its turn.

Cantrip: The Spellweaver casts a cantrip, at no drain to its spell point total.

Spellcasting: The Spellweaver draws power from either its Chromatic Disk or its own personal pool of spell points to cast a spell.

 

[Enrico Tomasetti]

I was working on this some while ago and I came up with this aprouche:

 

[MechaTarrasque]

I think the Legendary idea is particularly good one, as it elegantly handles casting more than one spell a turn. For something like this, I think I would have a separate list of spells for the legendary action (no concentration, pretty much all fire and forget zapping spells) with a mix of zapping, "save or suck", and buffer spells in the main list.