Ability to set up more than one @killcount command at a time
Description
@killcount is a great command, it allows players to keep track of their efforts through periods of time. That being said, I think the command is quite limited by the fact that we can only set it up for one mob at a time. Also, that effectively erases your previous kill count for whichever monster you had it set to track. My suggestion would be to replicate the command to allow people to track more than one monster at a time.
Rationale
There are many different reasons why people would want to track their kill count: for fun to see how many of the specified mob they've killed, to track their zeny/hour when farming, to track their luck when looking for rare drops and calculate odds, etc. Also, losing your previous progress on @killcount whenever you want to switch your target by reusing the command doesn't feel nice. I don't believe this is something that would actually impact the game in any way, I feel like it's more of a convenience thing - we never needed the @killcount command, yet it does exist, so why not make it better by allowing people to track multiple enemies?
Perhaps up to 3 monsters tracked would be enough, like @killcount1 / @killcount2 / @killcount3 - I'm not one to decide how many mobs people want to track. But I feel like at least, in that way, you're able to track all enemies you're currently farming in an area, such as Succubus, Incubus, and Abyssal Knights at Geffenia, for example, or the 3 MVPs you dedicate time to hunt. It's a minor thing, but I think some people would appreciate it, I certainly would.
Alternative suggestion (probably too much work)
Perhaps, another way to improve on this would be to keep the kill count data saved in a list, perhaps accessible through the Control Panel on a per character or per game account basis, but only allowing people to track mobs they've previously set a @killcount for (you know, not ALL mobs in the game). That being said, I think this would take waaaaay more time to develop than to replicate the command and allow people to set up 1-2 more @killcounts at a time.