Would an Artificer using Invisibility and Eldritch Cannon drop invisibility if they commanded the Cannon to fire?
Invisibility states: The spell ends for a target that attacks or casts a spell. Technically speaking, the Cannon is attacking, not the Artificer. Picturing my Artificer dropping the Cannon, moving away, using their BA to fire, then next turn using their action to cast Invisibility, moving again, and then using their BA to use the Cannon.
Force Ballista says: Make a ranged spell attack, originating from the cannon.
Flamethrower says: ...Each creature in that area must make a Dexterity saving throw against your spell save DC...
I'm reading this as you making the ranged spell attack or making them make a save, using your spellcasting ability, but the attack comes from the cannon's position. If the cannon was a separate entity it would have its own stat block like a familiar or homunculus; Rather, it's ruled as a "magical object" (but not a construct) that you are activating. Similar to a weapon, it is treated as an extension of yourself rather than its own thing. The Force Ballista is most definitely you making an attack and you casting a spell given the wording. The Flamthrower is a bit more ambiguous, since it does its thing and they make a saving throw against your spell save DC as if you cast a spell, but it doesn't explicitly state you're making a spell attack and Invisibility doesn't say you get revealed when you force them to make a saving throw. For consistency's sake I'd assume it was the same, but that one is probably better answered by your DM or Jeremy Crawford.
If the cannon was a separate entity it would have its own stat block like a familiar or homunculus
But it does....
It has 10 (+0) on every Ability Score. It has its own HP, its own Speed, and its own AC.
What part of all this makes you think it is not a separate entity??
I agree the wording on Force Ballista is weird, but I just assume it's meant to explain that the cannon uses your Spell Attack Bonus. It doesn't mean that you are the one CASTING a Spell. And invisibility says:
"The spell ends for a target that attacks or casts a spell"
You are neither taking the Attack Action nor CASTING a Spell
Very beginning of that same paragraph in black and white. It is most definitely not it's own entity. it is just a magical object.
Making an Attack also tends to cover anything that either requires that you make an attack roll or forces the enemy to make a save that is not explicitly a spell.
I don't know the answer for RAW, but myself I'll rule it this way:
-If you use the cannon as a separate entity/pet I'll let you stay invisible while commanding it to act, but the cannon itself will not become invisible.
-If you have a handhold cannon that you use as an item, it will become invisible when you become invisible and if you use it to attack then invisibility ends.
I don't know the answer for RAW, but myself I'll rule it this way:
-If you use the cannon as a separate entity/pet I'll let you stay invisible while commanding it to act, but the cannon itself will not become invisible.
-If you have a handhold cannon that you use as an item, it will become invisible when you become invisible and if you use it to attack then invisibility ends.
That's a fair compromise for a bit more advanced thinking than what the RaW really considers. I'd definitely agree with it if it was proposed to me.
1) If you turn invisible, the cannon is invisible or not depending on if you pick it up, like any other object.
2) The ballista firing will drop invisibility, because you are making an attack. It does not matter if you are carrying the cannon.
3) The other two modes will not drop it, as you are not attacking. The flamethrower mode is exactly like the dragon's breath spell in this regard - neither breaks invisibility.
Would an Artificer using Invisibility and Eldritch Cannon drop invisibility if they commanded the Cannon to fire?
Invisibility states: The spell ends for a target that attacks or casts a spell. Technically speaking, the Cannon is attacking, not the Artificer. Picturing my Artificer dropping the Cannon, moving away, using their BA to fire, then next turn using their action to cast Invisibility, moving again, and then using their BA to use the Cannon.
If you're gonna be a bear...be a Grizzly.
The Cannon got its own HPs, AC, immunities and saves. I view it as an individual entity just like a familiar.
I would rule that you give away your position because you need to somehow activate the cannon, but you stay invisible.
Attack: [roll]3d20dl2+6[/roll] Damage: [roll](if([roll:-1:critical], =0, 1d8, 2{1d8}.expand()))+4[/roll] Sneakattack: [roll](if([roll:-2:critical], =0, 2d6, 2{2d6}.expand()))[/roll]Yes.
Force Ballista says: Make a ranged spell attack, originating from the cannon.
Flamethrower says: ...Each creature in that area must make a Dexterity saving throw against your spell save DC...
I'm reading this as you making the ranged spell attack or making them make a save, using your spellcasting ability, but the attack comes from the cannon's position. If the cannon was a separate entity it would have its own stat block like a familiar or homunculus; Rather, it's ruled as a "magical object" (but not a construct) that you are activating. Similar to a weapon, it is treated as an extension of yourself rather than its own thing. The Force Ballista is most definitely you making an attack and you casting a spell given the wording. The Flamthrower is a bit more ambiguous, since it does its thing and they make a saving throw against your spell save DC as if you cast a spell, but it doesn't explicitly state you're making a spell attack and Invisibility doesn't say you get revealed when you force them to make a saving throw. For consistency's sake I'd assume it was the same, but that one is probably better answered by your DM or Jeremy Crawford.
But it does....
It has 10 (+0) on every Ability Score. It has its own HP, its own Speed, and its own AC.
What part of all this makes you think it is not a separate entity??
I agree the wording on Force Ballista is weird, but I just assume it's meant to explain that the cannon uses your Spell Attack Bonus. It doesn't mean that you are the one CASTING a Spell. And invisibility says:
"The spell ends for a target that attacks or casts a spell"
You are neither taking the Attack Action nor CASTING a Spell
"The cannon is a magical object."
Very beginning of that same paragraph in black and white. It is most definitely not it's own entity. it is just a magical object.
Making an Attack also tends to cover anything that either requires that you make an attack roll or forces the enemy to make a save that is not explicitly a spell.
I don't know the answer for RAW, but myself I'll rule it this way:
-If you use the cannon as a separate entity/pet I'll let you stay invisible while commanding it to act, but the cannon itself will not become invisible.
-If you have a handhold cannon that you use as an item, it will become invisible when you become invisible and if you use it to attack then invisibility ends.
That's a fair compromise for a bit more advanced thinking than what the RaW really considers. I'd definitely agree with it if it was proposed to me.
The RAW is this:
1) If you turn invisible, the cannon is invisible or not depending on if you pick it up, like any other object.
2) The ballista firing will drop invisibility, because you are making an attack. It does not matter if you are carrying the cannon.
3) The other two modes will not drop it, as you are not attacking. The flamethrower mode is exactly like the dragon's breath spell in this regard - neither breaks invisibility.