Taken from pathfinder, this encourages players to be more creative with their actions rather than burning their AP to attack.
MAP refers to a -5 penalty on attack rolls on the attack action consecutive usage of the attack action.. Regardless if previous hits had landed. This counts for the entire turn. Thus including reactions.
So if a character used 2 actions for 2 attacks and then makes an attack of opportunity as a reaction, the MAP for the attack of opportunity is -10 to the attack roll.
In LOR there are many ways of reducing the multi attack penalty from class traits, feats, weapons and equipment. Note that you cannot reduce the penalty until it becomes a positive.
When you reduce the penalty, you reduce the base penalty. Thus a reduction by one in the penalty makes it a -4. When stacking this makes it a -8, instead of a -10.