Roll20 Dice Vs Open Legend Dice Mechanics

I'm not great with coding or statistics, but I think I have noticed a problem with roll20's dice roller and how Open Legends Dice work. In open legend you roll dice and they explode. This works fine. But in open legend, when you have advantage you take the highest dice, then explode those. So order of operations is this. 1) Roll dice 2) choose the highest dice 3) check for explosion 4) explode dice 5) return result Currently this is used for rolling dice in roll20. 5d6!!kh1. But from what I understand it does this 1) Roll Dice 2) Check for Explosions 3) Explode dice and combine them together into a single result. IE 2,6+6+1, 6+2 = 2, 13, 8 4) Choose the highest result 5) return result But doesn't this mean that it chooses the best explosion possible out of all the dice? Would I be better using API custom rolling script?

Good question! Taking a look at the rules : When you have advantage on an action, roll an extra number of attribute dice equal to your advantage level. Then, when adding your dice together, ignore the lowest X attribute dice , in which X is your advantage level. Example of Advantage with Exploding Dice Imagine you have attribute score 4 and are rolling with advantage 2, you would roll 1d20 + 3d8 and keep the single highest of the d8s before rolling any exploding dice. Imagine your d20 rolls a 10 and your d8s land on 8, 8, and 3. You would then keep one of the 8s and discard the other two dice. Because the 8 rolled max, you may roll it again and add the result to your total. Imagine that lands on a 5. Your total score is 23 (10 + 8 + 5). So, the above example roll might look something like this in Roll20: /r 1d20 + [[ 1 [Attribute Dice] + ?{Advantage|2} ]]d6!!dl?{Advantage} Since we're using Compounding Dice (!!) instead of Exploding Dice (!): as you know, both an exploded die plus all of its additional rolls are summed together and treated as a single die by the dice engine. As such, a compounded attribute die can only be counted among the lowest if a number of other dice also exploded . (The total number of exploding dice in this case must be greater than or equal to the number of non-advantage attribute dice plus one. This is shown in the above example.) I can't imagine that this edge case would come up very frequently during gameplay, but when it does, it would indeed drop the lowest compounded die/dice. Consequently, the power of exploding dice is very slightly emphasized. This is not exactly how the game intends for rolls to be handled, but, in my opinion, making exploding dice very slightly more potent will not damage anything mathematically or thematically. All said, an API Script could be written that (for example), when given this edge case, drop a random compounded die/dice instead of the lowest one(s).

The exploding dice can't be used with keep because the explosion happens prior to the keep. and since we can't change the order, compounding was the first solution I thought of The problem pops up fairly often. when rolling 3d4 chances of two exploding is decent. and since your keeping 1, it will take the best explosion. or am I misunderstanding?  in addition since open legend to hit rolls determine damage, it skews combat more than a system that separates them.

Way said: The problem pops up fairly often. when rolling 3d4 chances of two exploding is decent. and since your keeping 1, it will take the best explosion. or am I misunderstanding? You're not misunderstanding. My understanding is that, if you normally have just one d4 attribute die and gain advantage 2 , each action roll of 3d4dl2 will have a 14.34% chance of encountering this issue . Within this exact situation, you can expect to roll an average of +2.05 higher than intended . (Therefore, advantage 2 on a 1d4 roll effectively provides a net +0.29 to hit over what is intended). Whether this is too advantagous for advantage 2 is entirely up to your judgment.