Help with a macro please.

How would someone make a roll that rolls a dice or set of dice twice, and adds the results together, but has a maximum of the original roll cap. Example: rolling 1d8, and it lands on 3. Then roll 1d8 again, it lands on 7. 3+7 = 10, but the maximum for the roll is 8, so it comes up as 8. This is something i want to add in a larger roll macro, because additional rolls and numbers need to be added into the same macro. The system this is for is Mythras, a Theism spell called "True (Weapon)". It rolls the weapon base damage twice up to a maximum of the highest damage it can deal, then adds damage modifier (also dice rolls) as normal.

[[ {2d8,8d1}kl1 ]] That will make a group containing  2d8 added together and 8d1 (a way to right a constant in dice notation, will always be 8), then will choose the lower number of the rolls in the group.

You'd just use the  Drop/Keep function along side  Grouping rolls for something like [[{2d8, 0d0+8}kl1]]  This will roll 2d8. compare it to 0d0+8  and keep the lower of the 2. 

Thank you very much!

Ooh.. Franky's answer is much better written.. I need more coffee... =D The reason 8 needs to be expressed as either 8d1 or 0d0+8 is because groups must contain a homogenous mix of values.  Either all numbers or all dice.  You could use inline rolls to turn the 2d8 into a pure number and do this: [[ { [[2d8]], 8}kl1 ]] But then you couldn't see what was actually rolled, which might be fine. There are lots of options depending on how you want it. =D

I'm a fan of [[ {2d8, {8} }kl1 ]]. The Aaron said: The reason 8 needs to be expressed as either 8d1 or 0d0+8 is because groups must contain a homogenous mix of values.  Either all numbers or all dice. Yup; that's documented here .