Even though I'm a big Planescape fan the only time I recall using any sort of modron was for a player character, but for some reason today I had this idea to make at least the cube-shaped modrons (duodrones?) into walking, self-changing Lament Configurations.
I figure that they'd each have a few configurations that let them summon various types of demons, bind creatures in hooked chains, and even manifest a region of hellspace around them. No limit to how many times they could "cast" a spell, but the casting time would be 1d4 or more rounds.
Level 2 Medium Construct
STR +0 DEX +0 WIS +1
CON +2 INT +3 CHA +0
Speed 30 feet
AC 12 DR 2 (metallic frame)
Fort +2 Ref +0 Will +1
Resist fire 10 Vulnerable radiant 5
Immune disease, poison, sleep, charms
Wounds 14 Vitality 0 Total 14
Gore +1 to hit; 1d6 piercing damage
Bladed Chains (1d4 rounds): One creature within 30 feet suffers 5d6+3 slashing damage and is restrained (DC 14 Strength check to break free). If the target succeeds on a DC 14 Reflex save, they suffer half damage and are not restrained. Each round the target is restrained it suffers an additional 1d6+3 slashing damage.
Summon Demon (1d6+1 rounds): The lesser hellcube summons 1d4+1 fallen ishim or 1 fallen cherubim. If a creature grapples the lesser hellcube, they can make an opposed Strength check to force it back into its original shape and banish the fallen angels.
While I could see using other modron types/shapes, in 4th Edition Dungeons & Dragons modrons can combine into more powerful types (and break back apart when quantity matters were than quality): I could see these guys doing a similar thing, forming into larger cubes to wield more powerful magic.
Now that the players have wrapped up The Golden Spiral in our bi-weeklyish A Sundered World FrankenFourth playtest campaign, it's Melissa's turn to (hopefully) run something, which gives me time to run with this idea. Coincidentally, the home-base island that the players cooked up is cube-shaped...
The Rogue is our latest alternate-addition to the Dungeon World core class roster. If you want something different and/or more flexible than the thief, be sure to check it out!
Just released our second adventure for A Sundered World, The Golden Spiral. If a snail-themed dungeon crawl is your oddly-specific thing, check it out!
By fan demand, we've mashed all of our 10+ Treasure volumes into one big magic item book, making it cheaper and more convenient to buy in print (which you can now do).