A new monster for D&D 5e: The Crystalline Claw

[Chauncymancer]

I'm designing a dungeon crawl, and in an area where the party will be level 2-4. It's a construct focused area of the game. I'm hoping to use the below monster paired with the CR 1 Animated Armor. I'm mostly wondering if this is going to be an appropriate monster to pair one to one with a CR 1 construct.

Crystalline Claw
HP 4d4+2 (18)
STR DEX CON INT WIS CHA
3 14 14 5 5 14

Damage Immunities poison, psychic
Condition Immunities blinded, charmed, deafened, exhaustion, frightened, paralyzed, petrified, poisoned

This automaton, less than a foot tall, is made of spun glass and fine soft metals. It's center is a glowing bruise-purple crystal the size of a fist, perched on three spier-like legs.

Antimagic Susceptibility: The Crystalline Claw is incapacitated while in the area of an antimagic field. If targeted by dispel magic, the Crystalline Claw must succeed on a Constitution saving throw against the caster’s spell save DC or fall unconscious for 1 minute.

Energizing Bolt: Target Construct within 30 ft heals 5 HP and takes a turn immediately, even if it has already acted this turn. This does not consume the Constructs turn. Crystalline Claws may not be targeted with this ability.

Arcing Bolt: +4 Ranged Magical Attack. The Crystalline Claw charges with infernal power, giving off arcs of bruise-purple energy. At the beginning of it's next turn, it targets one non-Construct within 30 ft. On a hit, that target takes 5 necrotic damage and the Crystalline Claw makes another Arcing Bolt attack against another non-construct within 30 ft of the first target. The Crystalline Claw may continue to attack until it has no valid targets or misses. No one creature may be targeted twice by the same Crystalline Claw in the same turn.

[BerzerkerUnit]

If you put it inside the armor it will seem like a “legendary” creature. It’s fine.

[Breccia]

Dispel magic should make it incapacitated, not unconscious. That way, you can make it immune to unconscious.

Also, why 5 necrotic damage? Why not 1d8?

Also, there's a risk -- even though you're the DM -- in a monster like this. If you had, say, an iron golem, why wouldn't you also have fifty of these things hanging around, giving it unlimited healing and enough turns to (yes I did calculate this) walk one hundred thirteen miles per hour? That's what I would do. They'd probably be in a giant adamantium basket, firing healing bolts and necro arcs through tiny arrow slits, and possibly flipping the PCs off. A simple restriction (no target can benefit more than once per round) won't stop your idea, but it will stop something ridiculous and dangerous. I'd also recommend making the claw unable to energize a construct with more hit dice (four) than it has.

I like the idea of the encounter you're setting up, but be careful, there's a risk you might be overlooking: AoE spells.

If the claw is inside the armor, taking its turn to give the armor an extra turn, some pretty basic spells like burning hands or thunderwave are going to hit them both, probably killing the claw before the PCs ever even see it. I don't think you want that, but at the same time, when the PCs realize there was a second creature inside the first, they are going to ask why their AoE's didn't hit it. Plan ahead. Either make the armor special with a giant extra-thick breastplate-like pilot cockpit, or fill the room with fragile and expensive items or friendly NPCs so they don't cast AoE's in the first place.

[Chauncymancer]

Dispel magic should make it incapacitated, not unconscious. That way, you can make it immune to unconscious.

I copy pasted that quality from the Animated Armor entry. I wouldn't want to change one without the other, and I'm loathe to change the MM entry unless there's an exploit I'm ignorant of.

Also, why 5 necrotic damage? Why not 1d8?

It's actually 1d6+2. I just prefer fixed damage values for special abilities.

Also, there's a risk -- even though you're the DM -- in a monster like this. If you had, say, an iron golem, why wouldn't you also have fifty of these things hanging around, giving it unlimited healing and enough turns to (yes I did calculate this) walk one hundred thirteen miles per hour? That's what I would do. They'd probably be in a giant adamantium basket, firing healing bolts and necro arcs through tiny arrow slits, and possibly flipping the PCs off. A simple restriction (no target can benefit more than once per round) won't stop your idea, but it will stop something ridiculous and dangerous. I'd also recommend making the claw unable to energize a construct with more hit dice (four) than it has.

This is actually the plot: Using ominous glowing necromantic crystals turned out to be a bad idea, and these guys are part of all the good terminator movie scenes rammed together.

I like the idea of the encounter you're setting up, but be careful, there's a risk you might be overlooking: AoE spells.

If the claw is inside the armor, taking its turn to give the armor an extra turn, some pretty basic spells like burning hands or thunderwave are going to hit them both, probably killing the claw before the PCs ever even see it. I don't think you want that, but at the same time, when the PCs realize there was a second creature inside the first, they are going to ask why their AoE's didn't hit it. Plan ahead. Either make the armor special with a giant extra-thick breastplate-like pilot cockpit, or fill the room with fragile and expensive items or friendly NPCs so they don't cast AoE's in the first place.

My plan is to introduce the first Claws as outside the armor encounters. (Haven't worked out how yet) and then to have maybe six of them in the big final boss battle of the dungeon zone powering up one big construct. "You aren't making any progress because this thing has fast healing 35 in minion form and super-haste." is how I want to put the 'puzzle-boss' in a boss that's otherwise a big sack of HP.

[Breccia]

I copy pasted that quality from the Animated Armor entry. I wouldn't want to change one without the other, and I'm loathe to change the MM entry unless there's an exploit I'm ignorant of.

Fair enough, my issue was mostly with "constructs shouldn't be affected by sleep spells". It's nothing you can't handwave.

It's actually 1d6+2. I just prefer fixed damage values for special abilities.

Ah. I don't, but that's personal preference.

This is actually the plot: Using ominous glowing necromantic crystals turned out to be a bad idea, and these guys are part of all the good terminator movie scenes rammed together.

...one's going to shoot a guy in the knee and spout a one-liner?

My plan is to introduce the first Claws as outside the armor encounters. (Haven't worked out how yet) and then to have maybe six of them in the big final boss battle of the dungeon zone powering up one big construct. "You aren't making any progress because this thing has fast healing 35 in minion form and super-haste." is how I want to put the 'puzzle-boss' in a boss that's otherwise a big sack of HP.

Outside the armor is easy: the first time, the PCs find animated armors and one of these Things crawls out and latches onto one. They see the effects and know the cause.

But please be careful with the six attacks. An iron golem with six attacks is really just six iron golems for the first couple of rounds. The massive spike in damage could be lethal before the PCs have any chance to act on it.

[Chauncymancer]

This is the big guy: The boss monster to the crystaline claws and the other constructs in the arm. Intended to be about 500 to 1000 xp and encountered between levels 3 and 7.

Two questions right off: Is this about in the ballpark for it's budget, and should Usurping Bolt be able to make spell casters cast a spell? What about a Cantrip?

Crystal Commander
HP (68)
AC 16
STR DEX CON INT WIS CHA
22 15 18 5 10 18
Damage Immunities:poison, psychic
Condition Immunities:blinded, charmed, deafened, exhaustion, frightened, paralyzed, petrified, poisoned
Sword Strike: +7 2d6+6
Multiattack: The Crystal Commander makes two attacks with its sword.

This creature appears to be a suit of ornate and highly ranked, albeit dated armor. There is a large purple crystal underneath it’s helmet, glowing. Similar crystals are visible at all of the armor’s joints and on the backs of its gauntlets.

Antimagic Susceptibility: The Crystal Commander is incapacitated while in the area of an antimagic field. If targeted by dispel magic, the Crystal Commander must succeed on a Constitution saving throw against the caster’s spell save DC or fall unconscious for 1 minute.

Commanding Bolt: Up to two target Constructs within 30 ft either make their next attack with advantage or make a saving throw now to end an ongoing effect. Constructs that have failed their save against dispel magic awaken immediately.

Usurping Bolt: +4 Ranged Magical Attack. The Crystal Commander charges with infernal power, giving off arcs of bruise-purple energy. At the beginning of it's next turn, it targets one non-Construct within 30 ft. That creature takes 2d6 damage and must make a DC 16 Wisdom Save. On a failure, the target makes one attack against a target of the Commander’s choice.