This is one of the biggest no-nos here at A Charmed World.
Deciding how other characters react to something, whether they get hit by your energy ball, making them talk or even have a certain kind of facial expression -unless they already established it in a prior post that exact info - is wrong.
You decide the reactions of your character, and your character only. It's not really a difficult concept to grasp. Just like in real life, you can't decide what others do, nor can you determine what happens to you if the forces behind said actions are outwith your hands - you just have to sit back and let things flow.
This not only goes for actual characters and players established in the World, but also for creating your own.
Although it doesn't seem like a big deal to just create a warlock while posting, having him blink in and then you kill him in the same post, it is just not the way things work around here. If a warlock is meant to blink in, then the warlock themself will post in the thread - not you.
A Charmed World takes a very strict view on this and any extreme cases of rule-breaking will be dealt with severly, in accordance to how bad the case is. Stay on the safe side - just don't do it.