[Voi]

Im asking for the most efficient(in cpu usage) way to detect client starting to use func_tank and stopping using it.
Metamod prints something like "start using tank" and "stopped using tank" on listen server.

[matsi]

#include <amxmodx>
#include <hamsandwich>

#define PLUGIN  "func_tank test"
#define AUTHOR  "matsi"
#define VERSION "1.0"

public plugin_init() 
{
    register_plugin( PLUGIN, VERSION, AUTHOR )
    RegisterHam( Ham_Use, "func_tank", "UseTank" );
}

public UseTank( this, idcaller, idactivator, use_type )
{
    if( !use_type )
    {
        client_print( idactivator, print_center, "stopped using tank" );
    }
    else
    {
        client_print( idactivator, print_center, "started using tank" );
    }
}

Don't know about efficiency thought.

[Elusive138]

If you want to stop it, just return HAM_SUPERCEDE.