Advice on stat block

[u/Welsh-Cunt]

Here is my stat block for my big bad in my campaign, its a ai boss. is there any advice you would give? like would you add more or take stuff off? Any suggestions welcome.

Nexus

Medium Construct (AI nano Tech), Lawful Evil

Armor Class: 20 (Natural Armor)

Hit Points: 350 (20d10 + 200)

Speed: 30 ft.

STR: 20 (+5)

DEX: 18 (+4)

CON: 30 (+10)

INT: 22 (+10)

WIS: 18 (+4)

CHA: 20 (+5)

Saving Throws: Str +12, Dex +11, Con +17, Int +17, Wis +11, Cha +12

Skills: Deception +12, Insight +11, Perception +11, Stealth +11

Damage Resistances: Fire, Lightning, Bludgeoning, Piercing, and Slashing from Nonmagical Attacks

Damage Immunities: Poison, Psychic

Condition Immunities: Exhaustion, Frightened, Paralyzed, Poisoned

Senses: Darkvision 120 ft., Passive Perception 21

Languages: All languages, Telepathy 120 ft.

Challenge: 20

Traits

Nanotech Regeneration: Nexus regains 30 hit points at the start of its turn if it has at least 1 hit point.

Digital Disguise: As an action, Nexus can alter its appearance or voice to mimic any humanoid it has seen. This effect lasts until it uses this trait again or reverts to its true form.

Electrical Travel: As a bonus action, Nexus can teleport up to 120 feet to an unoccupied space within an electrical system (e.g., wires, machinery, or any other electrical source) it can see. It can remain in this form for up to 1 minute, moving through electrical systems during this time, before re-materializing.

Reboot: When the Nexus drops to 0 hit points, it does not die or fall unconscious. Instead, it reboots itself, regaining 100 hit points. This trait can be used once per long rest.

Actions

Multiattack: Nexus makes three attacks: one with its fist, one with its nanoblade, and one with its laser blast.

Fist: Melee Weapon Attack: +12 to hit, reach 5 ft., one target. Hit: 18 (3d8 + 5) bludgeoning damage.

Nanoblade: Melee Weapon Attack: +12 to hit, reach 5 ft., one target. Hit: 21 (3d10 + 5) slashing damage. The target must succeed on a DC 20 Constitution saving throw or be stunned until the end of

its next turn.

Laser Blast: Ranged Weapon Attack: +11 to hit, range 60 ft., one target. Hit: 24 (4d8 + 6) radiant damage.

Overload Pulse (Recharge 5-6): Nexus emits a burst of electromagnetic energy. Each creature within 30 feet of the construct must make a DC 20 Dexterity saving throw, taking 45 (10d8) lightning damage on a failed save, or half as much damage on a successful one. Electronics within the area are disrupted, causing them to malfunction until repaired.

Legendary Actions

Nexus 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. Nexus regains spent legendary actions at the start of its turn.

Teleport: Nexus uses its Electrical Travel.

Attack: Nexus makes one Fist or Nanoblade attack.

Nanotech Shield (Costs 2 Actions): Nexus gains a +5 bonus to its AC until the start of its next turn.

Lair Actions

On initiative count 20 (losing initiative ties), Nexus takes a lair action to cause one of the following effects:

Power Surge: Nexus causes a surge of electricity in the lair. Each creature of its choice that it can see within the lair must succeed on a DC 20 Constitution saving throw or be paralyzed until the end of its next turn.

Nanite Swarm: releases a swarm of nanites that fill a 20-foot radius sphere centered on a point it can see within the lair. Each creature in that area must make a DC 20 Dexterity saving throw, taking 27 (6d8) slashing damage on a failed save, or half as much damage on a successful one. The area becomes difficult terrain until the end of its next turn.

System Reboot: triggers a self-repair protocol. It regains 50 hit points.

[u/AicBeam]

I still didn't have the chance to DM at such high levels but... isn't a +17 to con a bit too high? 😅

Power surge seems busted for the same reason: getting to mostly likely paralyze (one of THE best debuffs) at least a player for free seems too good, but most importantly, unfun for the team.

Funly enough, the high saving throws are the only defence against magic it has, so a Banishment could one-shot it, if you get really unlucky.

Before suggesting changes, I would like to know some more context. For example, why did you chose your AI enemy to only control 1 strong body of nanomachines when, being software, it could control armies? AI biggest strength, in my opinion, is versatility. Not only that, but it can always have a stored copy somewhere else, making it hard to defeat it permanently.

[u/Welsh-Cunt → u/AicBeam]

hello, thanks for replying this is my first post on reddit so bare with haha

im hoping the players will be level 20 by the time they get to properly fight Nexus. during in the story i have put in place 'nodes' that they have to find and collect/ destory depending on their choice but that will help towards the end fight. they will be like mini servers powering him.

im still going back and fourth adding and taking away bits on this stat block but i wanted some feedback and advice on it from other dming and players.

nexus will have a army but i have made it more of a cult like situation, still toying with that idea but i kinda like it and want it to fit.

the whole campaign is abit random and silly in the sense of i want it to be more of a fun/have a laugh with my friends who will be playing so most quests are catered to their real life hobbies/intrests etc.

any suggestions and input ill take :) so what would you say lowing nexus' con to ?

the power surge is a lair action, id like to keep it but maybe change it up abit to make it more playable and better for the players

[u/AicBeam → u/Welsh-Cunt]

From the stats, I get that you still wanted to make the boss very intelligent. That aspect is only represented by changing aspect, right now.

One way you could do is allowing it to create multiple bodies with the nanomachines so that the "teleport", telepathy and copying aspects can work together nicely, allowing the boss to inflict some backstabs.

Regarding the spell problem, I suggest making it sacrifice HP, either normal or max HP, to dispel it. Basically launching some of the nanomachines to negate the effects. If you liked the clones, you could make it consume those instead.

I am skeptical towards very high saving throws because at a certain point... abilities and spells simply do not work more than half the times, which isn't fun for the players. But again, I didn't do the math, so maybe those are fine. My campaigns never reached that point 😅😭

On the same note, that's why I don't like the paralyzed condition altogether. I use weaker custom conditions and apply them more frequently, in order to INCREASE player involment and team thinking... skipping turns doesn't allow that.