Explosive gems
 

The explosive gem, like (for instance) the Lock/Knock spell, seems to promote use at the extreme end. For Lock/Knock, if you're locking something, there's little reason not to use five locks (provided you have the time to safely rest and restore the fatigue). For the explosive gem, there's no reason not to put as much ST into it as you can. If there are enough apprentices in your area, this would be an 8d gem.

Apprentices cost $25 per week. If we don't require a full week's pay, but only $5 for an afternoon's Aid plus $5 for the ST used, then a wizard might spend $40 for the apprentices and $50 for the gem to make a 6d explosive gem. That's a good one-use attack for $90. Add $20 to max it out at 8d.

I was thinking that there should be something more than an extra cost of $10 per 1d damage. Now, to be fair, finding six apprentices is not a triviality in my game, so that puts a cap on how deadly a gem can be. But I was also thinking of increasing the cost of the gem required to hold the charge. I thought I might start it exponential and then switch to linear, something like:

1d: $25
2d: $50
3d: $100
4d: $200
5d: $400
6d: $600
7d: $800
8d: $1000

Perhaps this is a bit too expensive. Just finding a $1000 gem may be quite a chore, though an 8d attack is pretty darned large. A petard costs $2500. It's not easily comparable, since its 6d radius is 3MH and it does substantial damage to 6MH. I just mention it as the nearest comparable. But the average damage of 28 points for an 8d gem is nothing to scoff at.

Any thoughts?

Re: Explosive gems
 

I've been suggesting this for a while:
https://www.hcobb.com/tft/house_rules.html#iq14spells

Re: Explosive gems
 

I agree that the petard or grenade is an interesting comparison so far as the prices that you are proposing although probably not the best functional comparison.

I don't think that you have to make the gems more expensive to make them more powerful unless you believe that the gem must be larger to store more energy. ITL doesn't seem to suggest that but a GM can do what he thinks is fitting. I think that the nature of the gem creation spell by itself is somewhat restrictive in that it must be created all at once. You have already accurately referred to the number of apprentices needed to create more powerful gems at RAW, or near RAW, rates. The real restriction is the numbers of bodies available to make them.

I will use my wizard Hagen Physis as an example. He has the Explosive Gem Spell and has ST of 8 with no staff mana points yet. As is he could create several 1 Die Gems all by himself several times per day. I would say that $50 for the gem plus $10-20 each is fair. A total amount of time for casting and recovery of fatigue would be 1.5 hours per 1 Die Gem. Who would use such a small gem? A weak character with a sling that would otherwise be doing 1d-2 damage.

Now, by himself, if this same wizard wanted to make a 2 Die Gem, he would need 2 or 3 staff points or a 5 point power stone. Now, the cost for recovering ST becomes more that just resting. He would have to spend 7 ST and 3 staff points. He would have to rest for 1.75 hours to recover his fatigue and then 3 times of .75 hours recovery (2.25 hours total). So, recovery time for making a 2 Die Gem is 4 hours (0.5 workdays). If he had the staff or power stone points, he could make 2 per day (3 for a 12 hour workday).

So, I see it as a chart based upon recovery time.

1 die......1.5 hours
2 dice.....4 hours
3+ dice...Apprentices with Aid Spells

So, I see most games limited to 2, maybe 3, Die Gems per lack of availability of apprentices with Aid spells. So, really, the cost for these would be whatever the wizard can get away with charging.

My original thoughts for charge this wizard was $50 gem plus:
1 Die......$25
2 Die......$75
3 Die......$125
4 Die......$175
5 Die......$225
6 Die......$275
7 Die......$325
8 Die......$375
etc.

Cost isn't all that prohibitive on this chart. Each increment could be rounded up a bit if needed. It is roughly based upon the amount of time per die a wizard were to spend recharging assuming that he was using a base of 5 ST points and the rest coming from staff or power stones where each point of recovery requires 5 ST with a rest period for each of recovery. I created an Excel chart that came in just a little cheaper than this.

Like I said, the prohibitive part is finding enough wizards or one wizard with enough stored energy to do it. My game would be effectively limited to 2 or 3 Die gems with some special situations where larger damage gems could be made. I suspect a similar limitation for your game. Of course, Foe NPCs can have just about anything.

Re: Explosive gems
 

I agree with both of your approaches. Explosive Gems are broken as is.

Re: Explosive gems
 

Sounds good to me. I'd like to see the success of the enchantment being unknown so that duds are possible.

Re: Explosive gems
 

I've been debating whether they are even needed. How many kinds of boom-spheres do we really need?

Re: Explosive gems
 

I would be more accepting of that if the actual cost of the gems are relatively low. If your cost scale gets into the thousands of silver per gem, duds really shouldn't occur. TFT is tough enough to get ahead without ripping off PCs. At least, this is true for games that don't throw out treasure and coin like candy.

Gun power is defined with a certain amount of unreliability (1/6 per use). Explosive gems have not been defined in such a way. But, that one can ultimately be up to the GM for their game.

Re: Explosive gems
 

This is one of the few spells where rolling a 17 or 18 on your actual attack means make a new character please, unless of course Spell Shield provides total protection.

Re: Explosive gems
 

So you have. The only difference is that I halved the starting point ($25 for 1d rather than $50) and I didn't go all the way with the exponential growth.

Re: Explosive gems
 

I'm doubtful whether explosive gems are a good idea anyway. They tend to change the "We might die in this fight!" threat into "We may not make a profit from this fight," which is a lot less fun.