Actions that do damage but don't require a roll to hit-- Just roll me some damage from this source

As the GM, I've been wanting to add damage from environmental or continuing attacks to specific monsters.  For example, a fire damage that starts continues on successive rounds.  I'd like to have this damage rolled randomly, like an attack, but I don't need the attack roll (which seems to be required if I click the attack box).  I just want to prepare a statement of damage with a clear source and the effect notes.  You know, like we do with an attack.  So if I have 4d6 Fire Bolt as an attack that succeeds and does 2d6 on successive rounds I can give my critter the Fire Bolt attack and have another entry for Fire Bolt Burn that does 2d6 that is on the NPC sheet and I can add a note like "Con save negates and ends effect".  So, when I get back around to this critter I have a one click solution for taking care of the effect without pulling out the random dice roller, messing with it, and explaining what that number is for and any additional info I'd like included.  I've also wanted to add some trap effects the same way. I could make a pit trap NPC, throw in some info about how to clear/avoid the trap in the description, and have a damage action for the falling damage, with the note to make the Dex save for 1/2 damage.  I do this for dart throwing traps, and it's handy. The problem is that I can't figure out how to just have the effect roll damage so that it is formatted the same as the attacks.  Maybe there's some secret thing to put into the hit that will drop the Attack line?  "always" and "none" didn't seem work. I do not want to have to program a macro and hunt it down for every single effect in addition to building the NPCs.  I want it on the page with the associated critter.  

Which character sheet are you using, and are you willing to use API scripts? Or would you prefer to avoid them? It sounds like a Token Action is what you want. A simple macro to roll the damage, created on the character sheet for the trap, then assigned as a Token Action. The button to activate the macro and roll the damage will appear in the top left of the screen when you select a token linked to that sheet, and will disappear when you select anything else.

I finally figured it out.  All I needed to do was add an action, title it, and write out the text using double brackets [[2d6]] and I'd get a random number in the text with the output attributed to the monster and in the same style as the attack box.  In fact, I also discovered that I can click a token and get the text to reference the appropriate player.  So, for my remorhaz, there's a new action that's called "It BURNS" and the text reads " @{selected|token_name} touches the remorhaz or hits it with a melee attack while within 5 feet of it and takes [[3d6]] fire damage."  I can hit this in when the PC gets close and have that damage number linked to both my monster and the player affected. No need to write a macro!  I was really dreading writing macros for every effect I wanted, or constantly changing them if I wanted to avoid a massive list of macros, or switching tabs to find the macro which would be in the default box style vs. the 5e D&D style.    Yes, I'm still writing them out, but it's pretty simple text and I don't have to work with API or setting the layout.