Lost Lab of Kwalish

I don't see anything in chapter 9 that suggests you could use your casting ability modifier for the athletics check.  Didn't your armor have a thing about shoving, though? 

Athletics check: 6

The armor clatters to the ground. It's clearly still ready to resume hostility, it's just prone.

(Ooc: weird, all I did was correct the spelling of "clatters" not sure why that would fish the die roll.)

See, this is the hardest thing With initiative in pbp.  I think you're all waiting patiently and politely for your turn,  but if I tell you we're under initiative you're just going to air it's combat,  which is rarely the only way to resolve things in game.  (In truth, combat is usually the slowest way to resolve things).  That said, there is a hostile suit of power armor on the attack, so please indicate how PCs respond to this at your earliest convenience.

Leann draws ehr blade, but holds her action.  “Do you want it destroyed are are you trying to subdue it?” She asks.

"Subdue it. Magic armor is nice to study, but I don't need one more thing trying to kill me right now."

Wile, I propose two things to you: from the Battle Smith's description in ERftLW and TCoE: "When you attack with a magic weapon, you can use your Intelligence modifier, instead of Strength or Dexterity modifier, for the attack and damage rolls," and from the PHB, "[u]sing the Attack action, you can make a special melee attack to shove a creature... to knock it prone..." Huarache's shield is infused and thus magical. You are right that Huarache's armor can make a special shove, but I was trying to knock it prone on purpose, and in any case, Huarache's armor shoving requires moving in a straight line towards the target, requiring space Huarache doesn't have.

Finally, does there appear to be any special way to defeat the armor nonviolently? An energy cell to remove, perhaps?

I was actually thinking you might try to track with it,  or austere coverings it.  Presumably the guy you came looking for.  It's not a given that this will stop the fighting, it might actually make it harder.  Just consider the environment and yes, he can hear you. I explicitly said there was a monitor. It's 2 way.

Regarding the shield, I'm pretty confident that counts as armor not a weapon despite that it's used for a special attack action, thematically, it is uninvolved, mechanically.  Othetwise, it would only be an improvised weapon without a relevant feat or possibly a Maneuver (I don't have then memorized).  They're kind of the exceptions that prove the rule.  More generally it's a contest rolled with abilities, so if you had an item that boosted the relevant ability, that would work, but I still don't see int for shove.  

It’s irrelevant for now, due to a lucky roll, but I understand. 

"If you want me to attack the armor I can, but I will be attacking to destroy, not to subdue." Leann says, giving the others one more option to take the armor on without her getting involved.

You guys can fight the armor,  you won't"break" it.

It's literal plot armor

Leann shrugs and moves forward to the attack

To hit: 20  Damage: 8

To hit: 23 Damage: 11

Likely should have been with advantage, as the armor is prone, so here is advantage rolls:

to hit 1: 16 To hit 2: 10

Leann manages to hit the construct with the first strike, but the rapid erratic movements it makes prove too unpredictable for her to land a second blow.  In response se to the attack, while struggling to right itself, the smaller glass plate on the upper part of the armor's helm begins to glow a brilliant blue, from which launch four darts of [spell]magic missile[spell] at the assailant

X Leann: 15

At this point, we have entered combat. I'll post initiative in a moment... this does.not preclude the option of communicating with whatever controls the armor during combat - dialogue does not follow initiative order.

Armor ■

Huarache ■

Leann ■

Sam ☆

Omiy □

Samogri is up

I'm not going to bot, but let's see if Omiy will post.

Omiy is up, then Sam.  The armor is on the floor.

Actual spoiler:

Omiy will swing at the armor because why not.

Attack: 20 Damage:15 

Attack: 26 Damage:15 

"If you can hear me, stop this now." Leann nshouts at the top of her lungs. "We don't wish to fight you, but are here to help..."

Omiy lands a solid blow on the armor as if props itself up with one arm, blocking her next strike with the other as he painstakingly raises himself designed designed floor...

From within the helmet, a grainy, echoing, gnomish voice speaks. "The nine most terror-inducing words in Common: 'We don't wish to fight; were here to help' Here to help, eh?  Well young lady, just what is it you think you can help me with? Help yourself more likely."

<ooc: this dialogue is simultaneous to combat.  The shield guardian is upright,.but Samogri still has the initiative.  If he doesn't take an action by Wednesday @ noon, the initiative will revert to the armor.  Dialogue can continue in parallel."

sam will ready an action of attack "gnome man get out of amour"

"What could you possibly have that I would want?" Leann shoots back. "I am a paladin of Torm, not some treasure seeker. We were sent here to find a great inventor, not some spoiled child."

"Tell you what. If you come out of that armor, you have my word that I will not attack you without provocation."

"And what would you consider a provocation, lawful brother? (A reference to the Fraternity of Order emblem Huarache bears) Time will tell..."

"And you, the paladin of Torm. Of course, Torm.  Remi d me, where exactly does the god of Law make his divine realm exactly? Which of the seven heavens was it, again? Oh, yes, of course - Mercuria! I'm sure it's mere coincidence that its the same plane as the realm of Beldaari."

"And what, pray, is that staff you carry?" Referring to the Rod of the Mercurial, "it seems quite drawn to.my lab ware. But, I'm sure you have no interestin anything in my possession, no not the pious paladin if Torm. " 

"The rod was given to us to aid in finding you." Leann says with a glare at the monitor. "Not like we can simply walk to the nearest map-maker and ask for directions here after all." She sighs and puts away her sword. "This is useless, stop the armor from attacking us so we can speak like civilized people. I don't wish to destroy yet another of your inventions, but I will if you force my hand."

"Simple girl, here adults are at work on matters of import." The gnome say smugly through his electronic voicebox.

At this, a Large spectral hajd manifests before Leann and attempts to shove her back through the door through which she entered.

Bigby's hand Forceful hand 18 vs athletics.

On failure, Leann is pushed 40 feet through the door to the previous room. The hand stays with her throughout.