When the raid is fighting monsters, we need to use a way of determining what monster will be killed and when. This is the job of the Main Assist (or MA): Main Assist will tell the raid what monster to attack and when. The Main Assist will use a message in /rs, something like:
Person_01 tells the raid: Assist and Attack ** Monster_01 **
Person_01 voice-tells the raid: Battle!
At that moment, you should target the target of the raid main assist and start attacking it (more on the appropriate ways of attacking later). To make the task of targeting the correct monster easy, you can use several commands that you can put on your hotbuttons.
The most important and most useful command is /assist raid. This will put the target of the delegated Raid Main Assist to your target, no matter who the Raid Main Assist is. The other advantage of Raid Assist Delegation is that the target of the Main Assist is clearly marked by a big circle, so everyone can clearly see what target the Raid MA has. However, don't assume that every monster with a circle around it is the Main Assist's target; don't mistake the monsters marked by Raid Mark NPC to the one on Main Assist's target. All things related to Raid MA Delegation only work if the Raid Main Assist role has been delegated by the raid leader possessing the ability - but this is not a problem on the vast majority of our raids.
If the Delegate Raid Main Assist leadership ability is not available or if it's not possible to use it (especially in complex fights that may require to switch Main Assist during a fight), you will need to use the old-fashioned way: you will need to create a hotbutton for each possible person who can call assist (usually Main Assist and Secondary Assist, sometimes more), with the command /assist NameOfPerson. That will put the target of the specific person on your target.
It is very important not to choose your target via assisting before the Raid Assist calls it. One of the jobs of the Raid Assist is to choose the best possible target to kill - perhaps from a dozen monsters, perhaps after talking to the mezzers, perhaps after examining the health and abilities of each of the monsters in camp, perhaps it may not be easy to click on the specific monster immediately - so the Raid Assist may need to switch their target several times before finding the correct target. Thus, assisting too early will usually result in attacking the wrong monster; and even if the monster is correct, assisting and attacking too early can mean problems with aggro, because the Main Tank may not have gotten the chance to build enough of it.
Especially when the raid is moving fast and/or when there are a lot of monsters in the camp, the Main Assist may need to start looking for the next target even before the previous one is dead. If that happens, everyone will need to pay attention to it; again, assisting at the wrong moment could lead to attacking the wrong monsters. The Main Assist will however do this only when the current monster is at a very low health (at or below 10% approximately) - and at that time everyone already assisted, and the nukers have usually already started to cast their big nukes that will finish the monster in a few seconds - so this will most often not be an issue. However, it's something to keep on mind.
It is a very good idea to turn off automatic attacking on assists. This is done via the /assist off command - and once you type it once, your EverQuest client will remember the setting even after you log off and on again. By default, your autoattack will automatically turn on when you use the /assist command - and that would not be a good idea on raids (or even in groups).
If the Main Assist dies, the Secondary Assist (SA) will take over. When that happens, we will switch Raid MA Delegation to the new person, so you will still be able to use /assist raid without a problem. We will also switch the Raid MA Delegation every time we need a different person to start calling assists, if that's possible. One such situation would be a raid with a named monster that will summon adds during the fight (then probably the tank fighting the named will be MA for the beginning of the fight, but a different person will call assists on the adds when they spawn), and so on. Sometimes however the design of the event and the limitation of the Raid MA Delegation will not allow that - but that will be noted in /rs (one more reason to pay extra attention to /rs).