How can I set up a Roll20 macro to roll certain additional dice depending on the results of an initial die roll?

Question

I am playing a wonderful homebrew campaign running D&D 5E via Roll20 (I have a Basic account), and I have just rerolled as a wizard. One of my spells, prismatic spray, requires that I roll 1d8 for each creature, and based off that result, the target gets one of 8 effects afflicted upon them.

I am trying to find a macro - or find a way to make a macro - that rolls certain additional dice depending on the result of a die roll, since 6 out of the 8 effects of prismatic spray require further die rolls.

For example, if I cast this spell, and roll a 1 on the d8, I need to then roll 10d6. And I would have to repeat this process for every creature hit by the spell. I am trying to make this as easy as possible on both myself, my GM, and my team so that we don't end up just waiting for me to roll die, and I don't lose out on a great spell.

Answer 1

There is no way to do a Macro for Prismatic Spray as you want it.

While this isn't the answer you want, it is the truth. Macros can't make conditional statements or multiple separate dynamic rolls, for that you would need an API, but you're a basic user so it isn't an option for you. I discussed with some content creators from Roll20 and search other answers at the Roll20 community and their answers about doing this with only macros were all the same.

Answer 2

You can achieve those results using a call macro macro:

/em Dekkar Cast Elemental Infusion
/roll 1d6
[1](!
#ElFire ), [2](!
#ElFrost ), [3](!
#Elwind ), [4](!
#ElWater ), [5](!
#ElEarth ), [6](!
#ElLight )

and then have a macro with the appropriate names in your macro tab:

/me strikes out at the target!
@{Dekkar|wtype}&{template:atkdmg} {{mod=+5}} {{rname=Elemental Fire}} {{r1=[[@{Dekkar|d20}cs>20 + 3[STR] + 2[PROF]]]}} @{Dekkar|rtype}cs>20 + 3[STR] + 2[PROF]]]}} {{attack=1}} {{range=self}} {{damage=1}} {{dmg1flag=1}} {{dmg1=[[1d8 + 3[STR]]]}} {{dmg1type=Slashing }} {{damage=1}} {{dmg2flag=1}} {{dmg2=[[5]]}} {{dmg2type=Fire }} {{crit1=[[2d8[CRIT]]]}} {{desc=Channeling arcane energy into your weapon you cause an additional 5 fire damage each round for one  minute.}}   {{spelllevel=}} {{innate=}} {{globalattack=@{Dekkar|global_attack_mod}}} {{globaldamage=[[0]]}} {{globaldamagecrit=[[0]]}} {{globaldamagetype=@{Dekkar|global_damage_mod_type}}} ammo= @{Dekkar|charname_output}