[Sordrak]

The game allows a rapid burst of messages, yet i wouldn't recommend it.

I'm playing around with Map Pings as well, yet I'm not using any library and went for my own implementation. Yet, for such a small addon i wouldn't recommend this. Just use LibGroupSocket. LibGroupSocket should allow sending 3 respectively 7 bytes, which means a single message can transfer all you need. Use a new Message Identifier (first byte wich wasn't counted above) and send the kill count in another byte.

I guess the easiest way would be an update loop with a 1 second interval (1s seems to be a good time for not being kicked from the server for spamming) to send messages. For every kill you make increase a counter, once a message is sent set it to 0.

Shouldn't be a huge deal to implement this.

Regarding the question about simultaneous Map Pings by different group members. That's not an issue. It doesn't really matter if you are 2 players or 24 players in the group. It only matters how often you send something.

Edit: Seems like i have misread the last part. If you send a Map Ping, everyone in the group will see that Map Ping. So in a group of 24 it is sufficient to send one Map Ping with your information. Not 100% sure about how it is handled when someone is in a loading screen, i guess one will miss Map Pings in loading screens. So if that is part of your game, instead of sending an incremental amount of kills, you might go for sending the total kill count and a way to reset the count.