Next time you want to do something a little different but have no idea how the M&M rules support it, try the Universal Combat Maneuver:
1) Think of an appropriate description of your maneuver, including how it's different from your normal attack.
2) Use a Move action to perform the maneuver.
3) Take a +2 on either Attack, Damage or Defense and a -2 on one of the other two. The adjustments apply to your next attack and last for a full round.
The description can be anything you want, so long as it fits your character and at least vaguely describes why you are getting the bonus and penalty you picked. For example:
Stand very still and take careful aim with your bow, shooting more accurately but making yourself an easier target (+2 attack, -2 defense)
Grab a telephone pole and swing it wildly (+2 damage, -2 attack)
Use your telekinesis to hurl a spray of small rocks at your target instead of one big rock (+2 attack, -2 damage)
Throw up a sheet of fire to singe the werewolf and keep him away from you (+2 defense, -2 damage)
Dig in and channel the spirit of the thunder god and throw sizzling bolts of electrical death (+2 damage, -2 defense)
There are as many as you can think of. They can be actions specific to the character (“I'm doubling-down on my wrist gattling guns!”) or they can be based on the situation or the environment (“Water on the floor? Instead of grabbing him I'll lean down and electrify it with my Shock Gauntlets!”).
The same move doesn't have to use the same bonus and penalty each time. It all depends on how it is described. One round Uber Girl picks up a telephone pole and takes a vicious wild swing (+2 damage, -2 attack). Later she picks up a similar pole and swings it in a broad arc that's hard to avoid, but throws herself off-balance in the process (+2 attack, -2 defense).
The idea is to encourage players (and the GM) to come up with creative descriptions in combat, and let them adjust the odds a little bit in the process.
Superhero games are about doing cool stuff. Not just brave or heroic deeds, but fantastic, impressive, and sometimes completely implausible feats. Superheroes throw buildings at people or melt steel girders with their laser eyes.
M&M combat is fun, but in the end it's d20, and that means you are often doing the same thing over and over: rolling the same attack each round and seeing if you hit. Some characters have interesting choices all the time (like those tricksters with their feints, taunts and redirects), but the average superhero archetype has one prominent choice each round: attack!
Tactically that's not interesting. Even worse, because by the rules you are taking the same action over and over again (same roll, same bonus, same damage if you hit) you can get lulled into visualizing the character as doing the same thing too. Instead of seeing a dynamic super-powered slugfest, you're seeing boring punch-punch-punch-punch. When you make tactical choices, you visualize the situation more dynamically and dramatically whether you intended to or not, because you are seeing what is going on and what effect your choices have.
So tactical choices encourage color, but if you make a rule to cover each possible action or interesting move you'll have a big, big book of combat maneuvers, and you'll spend all your time flipping through it instead of playing the game, and you'll still just be telling people what is possible instead of letting them use their imagination. Stifling creativity = not good.
The move action to do the maneuver is in addition to whatever action you normally need to perform the attack. So if you want to punch someone (standard action) you need to spend a standard action in addition to the move action to do the maneuver. Move + standard takes up your whole round. You couldn't run across the street (move action), use a maneuver (second move action), and still attack in the same round.
The adjustment only lasts one round, so if you want to do it again next round, spend another move action to pick up another telephone pole after the first shattered, aim again, etc.
Yes, it gives everyone a weaker version of power attack, defensive attack, accurate attack and all-out attack, but with the added cost of a move action. If you already have those feats you can use them instead. Since the Universal Combat Manuever is only a two point shift instead of the five point shift from the feats, it let's everyone have a little more latitude without radically changing their PL balance (a character who can do 10 damage normally can swing only from 8-12 with the UCM, instead of 5-15 with a feat).
Yes, it replaces or trumps lots of others maneuvers (improvised weapons, aim, aggressive stance, etc). There could still be cases where you'd rather use the existing maneuver because it doesn't take a move action. The advantage is simplicity, which means (hopefully) players will spend more time thinking of cool descriptions of maneuvers and less time figuring out whether there is a way to do what they want in the rules.
No, it does not stack with other manuevers or feats that it logically replaces. You can't use the Universal Combat Maneuver along with Power Attack or Defensive Stance (for example), but you could use it with something like Sneak Attack or Grapple. [added 04/21/07]
Yes, you could use the same idea in any d20 game. If damage doesn't use a d20 the way M&M and True20 does, you'll have to sort out what the bonus should be.