I prefer to try to handle actions in character, with a healthy mesh of out of character cushioning.
Enter the essay.
Everyone wants to be acknowledged, and it's completely disrespectful to blatantly ignore someone. While I understand there is a mild problem with overpowered characters flexing their abilities on the inhabitants of Gambit's Bar, is it right to ignore these players?
I don't think it is right to ignore these characters, but to respond with perspective. If their character truly is a God, and the God acts brashly, activate In Character repercussions. Hide under tables, cower in fear, call 911. Acknowledge what they are doing, and how they are effecting the environment.
It is important, in my experience, to also guide the player through their powers. Many newer players, or players that come from competitive sites (as zernin did) don't understand the 'you can't auto hit' thing. Sometimes, it comes down to offering to write their post for them, simply so they can see where they wrote "Chopped off their head" instead of "Swung at an extremely high velocity at their head".
So long as you are polite, and don't jump down their throat, whispering them instead of calling them out, I find this tactic to work very, very well.
The key is to remember that they are, at the end of the day, a fellow player. Behind that God is someone, and it's best to whisper them and find out what's going on. Be polite. Don't use grammar that can be easily construed as being snarky, like this sentence was, and don't confuse the heck out of them or use terms like "you shouldn't" or "don't". Introduce yourself, use a smiley. If someone complains, seize that opportunity and message them. Help them through, because you can't expect someone to learn if nobody is willing to teach them.
As for split universes, that does not make a solution, it simply gives everyone the impression that it is ok to ignore a player. It is ok to ignore anyone's actions, and completely forget we are all in one role play. It is ok to disregard someone else's impact on the Multiverse, and as they say in Improv, Ignore an Offer. By doing this you are telling the very player you want to improve that it is ok to ignore people. With this logic, the power player can now do whatever the hell they want, for this is their dimension/universe, so hardy har deal with it.
This is not the attitude we should be passing through the Multiverse, through Role Play Gateway, that it is alright to ignore a player, a writer, a character.
As a community, we are as we treat our worst off. The proper way of handling these players who most of the time honestly don't know better is to treat them exactly how you would treat yourself, if the roles were switched. Teach them. Enter their shoes, remember how intimidating the OOC Chat was the first time you walked in. Remember what it was like the first time your character was ignored, or you just wanted to be a part of something amazing.