I'm not sure I understand your question.  Perhaps you can explain specifically what you are trying to do.  Are you trying to convert D&D weapon damage using polyheadrals to BoL D6, for example? If so, no exact translation is possible - only an approximation.  Also, BoL damage as written works pretty well, so it might help us help you if we knew why you were trying to translate it.  If we knew your goals, it might help us to provide an answer.

Hmm... well, I see what you are trying to do and unfortunatly, I don't have a solid answer.  The two games don't translate very well mostly because of character levels and what HP represents.  BoL characters have fairly static hitpoints or lifeblood with a narrow range centered on 10.  With an average weapon doing D6+STR, damage in BoL is slightly less abstract than it is in D&D.

 In D&D, a first level wizard might have 4-5 HP, and a 10th level Barbarian might have 100 HP so there is a huge swing in the amount of damage that a human body can take.  HP in D&D are more abstract representing sweat, confidence and other intangibles that are represented in BoL with hero points.  If you really want to systematically translate D&D HP and damage to BoL lifeblood, you should probably pick a D&D level that you want your BoL game to represent.  2d10 claws will flay a first level party like a cheese grater but are less scary against a 12th level party.  Mathematically, you could pick a level (say 5th), find average HP for each character type, take a common weapon like a sword for a baseline, convert to a pecentage or ratio, and translate into D6 plus or minus vs lifeblood, and then do the same for other damage types.

It is doable, but then BoL characters have hero points, so the whole formula is for naught unless you remove or limit them.  I have three suggestions for you to consider - though it is your game so take them with a grain of salt:

First, just try BoL as is.  It works.  In fact, it works better than D&D.  The drastic swing of abstract character level HP is one of the things that sent me searching for other RPGs way back in 1982 and it has never been "fixed."  I like D&D warts and all, but HP and damage is one of the D&D's "loveable" flaws IMHO.

Second, eyeball it.  That's what I would do.  You are talking about random numbers so exact translations aren't necessary.

Third, and this is a bit wonky: do you have Chaosium's BRP?  The reason I ask is that BRP HP is very close to BoL lifeblood in terms of actual numbers and aproximate abstraction (BRP HP is slightly more "real," graphic and gory with certain options, but the basic system is close with the average character having 8-15 HP without ever gaining more).  BRP also uses polyhedrals for damage.  A person could use BRP damage with BoL without much or hiccup.  It would make for slightly more deadly game (a BRP sword does d8+1+ STR) unless you adjusted lifeblood up a little bit. 

But really your best option is #1.

I hope that is all more helpful than confusing.

I kit-bash games all the time and write others from scratch.  I think many good GMs do, so no, you are not alone in this.  I also use D&D monsters for BoL without much worry by eyeballing - though I understand that you are looking for something more concrete. 

Just a shot in the dark, but you could try dividing D&D max damage by 2 (or whatever number works for you for fourth level characters in the edition of D&D that you are using) and using that result as the BoL max. So 3d6 = max 9 in Bol, or D6+3, or D6+D3 to better approximate the minimum and curve of 3d6.  That could give you a guideline at least.  If it doesn't feel quite right, then adjust to taste.

There is a lot more monsters now in mythic than their used to be.  Reading through them should give you an approximation of what monster damage should be.  Because BoL stats are so simple, you can generate a Bodog or whatever else in a couple of minutes, and once you have converted a few monsters, it should become second nature pretty quick. 

I realize that I am dodging your question a little bit, but that is just because I am an improvisational GM that would approach it intuitively during play, unless I was writing a monster book or something.  Perhaps someone else can chime in and give you a better formula.

Maybe I've been approaching this wrong. Has anyone figured out what the 'average' roll is on 1d6H and 1d6L? 

thanks!

Chaosmeister wrote:

I use www.anydice.com to see propabillities and the like.

http://anydice.com/program/6211

"Average" for 2dH is 4.47 for 2dL 2.53

Do you really mean 1d6H and 1d6L? I'm not familar with that program!

Thanks!