Latency

When a player is suffering a lag it means their computer or internet connection is causing a delay in their awareness of what is going on in the game. When a party is attacking a mob, a lagging player will see monsters in places they no longer occupy, will hit monsters that have already died and react to conditions that no longer persist. e.g. Try to heal someone who is dead or remove a hex that is no longer there. In the eyes of the party, the player will be standing around, then running at a corpse, then casting a meaningless spell. In a very bad case of lag a player may not be able to move at all for a short amount of time.

A player who is lagging should let his/her party know so they can account for that.