Whoops, went back and re-read the rules on Bendalloy. Your comment makes more sense now; they shouldn't get "more Beats", by the looks of it, though they'll get some extra dice to the attack. I don't know where I was getting the 'penalty' idea from, but it looks like defenders on the other side of the bubble get Cadmium/Bendalloy free Defense dice, and Bendalloy specifically grants +Bendalloy dice to the attacker as well.

I'm struggling to visualize a bit why they couldn't make more attacks when they're moving 20x as fast, but I like where this is going.

On some level, I do regret handing out such dramatic new metals, but the politics surrounding them have been great fun. The players have come up with many creative applications that don't cause me headaches, too.

1) Time-bubbles deflect/alter the flight path of all fast-moving projectiles crossing their borders. Thus, a coinshot cannot shoot attacks through a time bubble at characters outside of it (at least, not without major troubles)

Isn't the penalty equal to the Cadmium/Bendalloy rating of the bubble's creator? Which, since the Bendalloy is impure, is a mere 2.

2) Characters only get one action per Beat. If using Cadmium to slow down time inside the bubble, they'll still just get a single shot. The best that character can do IF the Mistborn could drop the bubble fast enough for the Coinshot (and I would say given the speed the coins travel it'd be nearly impossible at my table) the best the Coinshot could hope for is a single Multiple Targets shot.

They're using Bendalloy, not Cadmium, for this purpose. Inverting the process by having the Cadmium-burner get close and suspend the target, then have Coinshots fire at him from outside.

My understanding was that we'd get a shift in Beat length, for the characters inside the bubble. For Bendalloy, they'd essentially have 20 Beats pass before we took another Beat for all other characters.

Okay, I need help with this one. I can't think of any reason it shouldn't work, and it actually makes some sense, but I'm concerned about encounters being trivialized.

The campaign that I've been running is about the secret discovery of Cadmium, and soon thereafter its alloy companion by a House Bendott, during the events of The Final Empire. The PCs are in on this secret by now, and have access to a healthy stockpile of Cadmium, and also possess a few non-renewable impure Misting vials of "Bendott's Alloy".

They're expecting a big physical assault soon, and they've come up with a combat application of this Bendott's Alloy that seems extremely potent: they'll have the party Mistborn down some Bendalloy and set up a bubble that contains the quite skilled team Coinshot. Said Coinshot will then fire a massive number of coins at all visible targets, then drop the bubble and watch as they must defend themselves from a massive number of attacks.

He's got Steel 7, which won't be significantly hampered by the effective Bendalloy penalty of 2. Somewhat irritatingly to me, while 20x speed is probably still plenty enough for this feat, the impurity actually seems to work in their favor, used in this manner.

Are there any issues with this that anyone can see? (Please say yes... it seems like it would trivialize most encounters)

Game mechanics for stifling what characters are allowed to do are often poorly received. At the very least, I'd look in to exploring making it function on a carrot paradigm rather than a stick; give them a reason to be loyal.

That said, I think you'd be better served just giving them actual reasons they'd want to be loyal, and let them make up their own minds which side matters more to them.

Sent, along with some S&H coverage! Thanks mate.

I'd also be keenly interested in the Elite set.

Yeah... those dice look great, and my heart totally fell a bit when I read they'd only be available at the con.

Wow, this is getting way too technical, even for Brandon's concepts.

Yeah... I agree. I probably should have been more careful handing out this particular metal to my group of players.

Thanks for the answer!

That won't work for a group of science nerds.  Stationary has no meaning without defining a frame of reference (stationary relative to the planet, stationary relative to the train, etc).  The planet itself is moving (which was established in Hero of Ages, so no trying to claim it's a stationary planet that has a sun orbiting it or some crazy thing) and is actually a non-Newtonian reference frame (though for most purposes it could be considered one).  On a moving train could also be generally considered a Newtonian reference frame for most of the trip, and from the physics sense is no less valid of a definition of "stationary" than the planet.

I'm really inclined to be a bit annoyed and insist that the reference frame is the planet itself, because that's how it always seemed to work in the books. No idea what that means with respect to Sanderson's future scifi Mistborn, but this seems an acceptable means to maintain part of my sanity for now.

So, Pat's suggestion matches my intuition in that case as well. The open quandry that remains is: the bubble is smaller than the carriage, so one of the following must happen:
1) Part of the carriage (the seats, etc) are inside the bubble, so the whole carriage is Cadmium slowed, even the parts outside the bubble.
2) The parts of the carriage that are inside the bubble are affected, but the parts outside are not. This is probably going to result in an exploding carriage as weird forces act on it.
3) Since parts of the carriage are outside the bubble, none of it is affected. The Cadmium users inside the carriage will perceive the seats approaching them at very high velocity...

1 kind of seems the easiest to me, but probably makes the least sense... I'd assume the bubbles frequently touch the ground, and I don't think the entire planet gets Cadmium slowed.

Thanks.

Ugh... now I need some help on my latest headache, the interaction of Cadmium bubbles with larger objects in motion. In particular, they want to know 'what happens if I create a Cadmium bubble inside the cab of a carriage, but too small to engulf the carriage itself?'. Similar questions have been made about using it in hypothetical train cars and such. "The bubble remains stationary" is causing all kinds of questions of 'what reference frame' from my group of science nerds. I hate them sometimes.

I thought it was always Outcome vs Difficulty that determines success or failure+complications. So, in this case, you fail with one consequence.

That makes sense, thank you.

I've got two more questions my players have brought up...

1) What are the minimum radii and time differentials that are possible with Cadmium and Bendalloy? I'm worried about what he's planning with this one...

2) Suppose a Mistborn is burning Copper, and he's interacting with another character that he suspects to be an Allomancer of some sort. If he burns Bronze, is he able to 'see through' his own Coppercloud?

Huzzah!

Are the two targets within each other's coppercloud (ten paces)? If so, I would just use the higher Copper rating.

Not in this case, plus without a Stunt the mental protection only applies to the Copper-burner themselves.

Since the Rioter is attacking multiple targets, I assume (it is not clearly stated how this works) it functions the same as the Multiple Targets Stunt for Steel/Iron: Create your pool, roll once, each target defends seperately and compares against your roll. However, Copper subtracts its rating from the Rioter's dice pool. If each target has a distinct Copper rating, this has me confused how to form that single pool for the Rioter.