Powergaming and Metagaming
It's not cool.
What is powergaming? Powergaming is a pose where you pose the results of another character's interaction over with yourself or in a scene without their permission. It can be something like posing their reaction over to your character or scenario, or posing the results of actions upon them.
Also powergaming can be forcibly posing the results of actions, such as hitting someone or the damage from an attack without someone's permission. It can also be putting someone in circumstances where they have no options or are forced to take an action and the results are coerced.
A powerpose might be 'Thing hits Abomination with all his strength, and Abomination staggers backwards, completely stunned and disoriented' when someone else is posing Abomination. Thing is posing the result of his attack over on Abomination.
Powergaming can also be abuse of powers or circumstances without consent, such as Quicksilver going 'Quicksilver is so fast, that no one can touch him this round and no one can remotely land a shot on him'.,This is possibly within his powerset, but not conducive over to the scene. It states that any particular action taken against him will fail.
Powergaming can also be as a result of posing powers (such as pheromones, mind control) or circumstances no one can possibly resist or react to (someone with superspeed, grabbing someone so they can't move, knocking someone out) or circumstances where there is no option and participation or doing things in such a manner is enforced (abusing IC authority by humiliating someone or giving them unreasonable orders, having someone completely resistant to all effects to stop them or invulnerable to things, having characters perform unreasonable actions in circumstances or not giving other characters attempts to stop them or interrupt, etc).
With everything, it's always best to pose attempt and then let someone else pose the result, or if you want to do something to another character or setup someone is emitting, to ask them first. As always, if unsure ask, and pose as an attempt then without the consent of another player, and it's helpful in such things to let other participants in the scene know quickly so as to not interrupt the flow of things.
The easy definition of Metagaming is using OOC knowledge for IC gain when the character would otherwise not have that information. This is when you as a player know something (ie, Bruce Wayne is Batman) and then you roleplay your character as having that information. Unless you?re on a short list of people that Batman trusts to have his identity, or one of his few enemies that know his identity (see Talia al Ghul) then it?s pretty much going to be metagaming if your character knows who he is.
Another example of Metagaming is having knowledge of cutscenes or logs that your character was not ICly present for, or knowledge that is given in a pose but not outright said. If a character is lying they may pose that they are for the awareness of the player, but your character may not have any means of knowing they are lying. Even someone like Jean Grey can and has been lied to numerous times canonically, and been unaware until a later point.