I better get this out of the way. Magical Engineering Commandos (MECs), it's a term I use to describe a type of player. Well, a type of player AND a player mentality. You grow up in an Engineering town with lots of folks who tend to work in the IT, Engineering, and Space fields they tend to crop of. At first you might mistake them for Rules Lawyers, Muchkins, or just Power Gamers. But as time goes on you soon discover they are not out to hurt or sabotage your fun. No, they're playing a different game than you were expecting, they're looking at challenges, the rules presented by the game, and their resources at hand...and they hey solve problems. Creatively, explosively, and generally in manners to make most GM's jaw hit the floor and bounce.
Let me spin you some examples:
One session of GURPS Fantasy "With GUNS!" in my own setting the group go their hands on a High Mana zone, a highly skilled PC enchanter, and a lot of power stones. (All through play.) What they churned out was: self reloading guns with ammo pouches that self filled between shots, quick fatigue recharge wands dedicated to just doing that so they got their power back faster, self guided satchel charges that flew to their targets, guns that upped their accuracy, and...well, I can only call it the magical auto cannon. You'd have to see it in play to understand what I mean. The group always went in armed to the teeth, well prepared with gear and resources, and recon was the word of the day. They LOVED to scout and ambush. It was "The Way". Hell one of the players developed a spell recon combo called "Captain Air Biscuit" which was Body of Air, Invisibility, and Shape Air that allowed him to sneak around better than some ninjas!
Another group of MECs in a different game of D&D3E started kitting themselves out in magical gear. Everyone picked up crafting skills to help out, they were spreading the exp cost around. They were developing a special 'kit' for all the players. Rods of Prestidigitation, Wands of Cure Light Wounds (for clerics AND bards), cloaks of flying, boots of striding and leaping, gloves of climbing, bracers of armor, rings of feather fall, rings of substance. The idea was to allow the PCs to enter ANY environment and move around with little hindrance. They were all about mobility and speed. In combat they struck fast, hammered the foes lines, and snuck out again. Yes, magical guerrilla tactics.And boy did it work. Once in an arena fight they had their part monk layered in so many persistent buffs he all but glowed from the effects. (Then again this was in 3.X when trip combos were abusive.)
I...I shudder to talk about how zany things got in Exalted. Demonic Mailboxes, party teleporters, Instant bases, the list goes on. Once they discovered the raw utility of summoning magic things got bonkers FAST.
The list goes on, but the playstyle remains. The group fights as a unit, protects each other, covers weaknesses, and most of all looks for ways to enhance their abilities. The Fantasy version of a Shadowrun team, or hell a modern Special Forces unit, mixed in with some crazy problem solving. It also involves a lot of flat out being sneaky and taking advantage of the rules and setting mechanics to the groups benefits.
My advice to a GM that runs into these players? Nurture it, but keep it focused on the fun of all the players....and take notes! NPCs might adapt their tactics too. Just saying.