While I understand the @useskill adds some fun to playing style, I suggest the removal of it. There are cases where new players got forced into Frenzy mode with the use of @useskill, and had to relog. The players would then spam the skill whenever the player relogged and so he is unable to do anything.
Apparently these people have nothing better to do, and spams it on every newcomer at the newbie zone. I cannot remember the names, but I'm sure there are people lame enough to do that. The only rule stated that they had to respect other players, but apparently this isn't the case.
It's just an insight. I'm not a victim of this... yet. But I seen it myself. I won't be whining either lol. I know you won't be bothering with in game politics, but at least give it a thought =D
Along the same line, a loophole in the custom monster summoning is also through the use of @useskill. The player just have to spam Monster Chant, and Prontera was flooded with monsters. The monsters remain even after the player logged out.