//topo
new bool:dm[MAX_PLAYERS];

//quando ele for Pra arena
dm[playerid] = true;

//onplayerdeath
public OnPlayerDeath(playerid, killerid, reason) {
    new s[128];
    if(dm[playerid]) {
        format(s, 128, "%s matou %s na arena!", name(killerid), name(playerid));
        SendClientMessageToAll(-1, s);
        dm[playerid] = false;
    }
    return true;
}

//fim
name(playerid) {
    new n[24];
    GetPlayerName(playerid, n, 24);
    return n;
}