So this was the last of our “pre-campaign” adventures. Setting up our characters to be amenable to taking on a business partner and launching their own Mercenary for hire business.
This adventure featured some displaced Modrons as the centerpiece for a moderately tactical combat session. So, here’s the crunchy bits of what we did:
We were inspired by this snippet from the Monster Manual entry on Modrons:

We read that and thought, “That’s a neat idea that Modrons getting destroyed promote other Modrons. It would be tons of game-play fun if you had Modrons leveling up mid-combat as others were destroyed…” Then we realized; we play in a home-brew campaign setting. So, Modrons in OUR world don’t have to work exactly like RAW (Rules As Written) Modrons! This means, we tweaked it! We changed how Modron destruction works as follows:
When a Modron is destroyed it’s matter and energy bond with the nearest Modron of EQUAL rank to it. This transforms the Modron into the next higher level of Modron. It can only work for boosting a Modron of EQUAL level. Also: newly promoted Modrons roll into existence with their full prescribed HP.
So bashing a Monodrone to pieces will boost a nearby Monodrone to a Duodrone. But if you have a Monodrone and a Tridrone left but nothing else nearby and you bash either… nothing. This built i a mechanic that could be strategically used if it was ever sorted it, it wasn’t but the opportunity was built in.
This was Smashing fun for the DM! Especially since Modrons get more attacks per round as they bump up. This means that if things fall in the right way a party could thin the herd of Modrons without effecting the action economy of the combat!*
We also had a wheel in the center of the 60’x60’x60′ cube room they were trapped in for the duration of the combat (see our campaign diary post here: Campaign Diary ) This wheel changed the room (it moved like a Rubik’s cube) and spawned more Modrons for the next encounter. Breaking up encounters did a few interesting things: If players had wanted to they could have taken short rests. It also provided a break that burned up many buffs like certain concentration spells and killed barbarian rages. During the first of these room changes the party had to make DC12 dex saves or begin the opening round of the next combat prone. The room movement before the last encounter was more sporadic and required a DC15 dex save or they take 1d6 bludgeoning damage and start the first round prone. They rolled pretty good dex saves so it wasn’t a huge issue but it did come into play as some melee characters couldn’t engage in the first rounds with half their movement burned standing up.
Other strategic moves we used: Some modrons can fly… fly is nearly always frustrated to characters without a strong ranged attack option. In one of the changes two bridges flipped out and Modron’s used these to launch javelin attacks from on-high. We even had them lie prone giving them 3/4 cover for a round while they made preparations to change gears mid-battle.
To the parties credit the dwarven druid used his wild shape ability to great tactical advantage spidering all over some Modrons!
Something we won’t do again: One of us builds durable packaging sometimes at our work so has access to scrap closed cell foam. We used this to make a simple battle-structure to convey that all this happened in a 60′ cube. We won’t do it again because even though we made the front very cut-down it made keeping track of what was going on in the field of play pretty difficult as you had to peer into the cube-o-death we’d made. We really did it so the bridges would make sense spatially, but next time we’ll just use an elevated stand or something to get that imagery across on a battle-mat.
Anyway, here’s our bad idea- or our poor execution (behold and learn from our mistakes):


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If you DM thinking in action economy is crucial to keep combat interesting. Players all have: an action, a bonus action, movement, and a reaction to burn every round. Many low level monsters are lacking bonus actions. It’s easy in any level of combat for the party to have a flood of actions then the enemies to get a scant hand-ful, then another flood of player actions. If you want to keep combat interesting try to even out the action economy some (Action economy is why big monsters get legendary actions by the way)… anyway, i’m sure we’ll talk about action economy again at some point.