Making a KillAura module for 1.9/1.10

float cooldown = 0;

public void onUpdate() {
    //Check whether or not the current module is enabled. If your update method is only called when this is true, ignore this line.
    if (!isEnabled()) return;

    //Handle whether or not the player should attack
    if (float cooldown > 0){
        //There is still a cooldown active. Decrement cooldown by 1, and wait for the next update.
        cooldown--;
        return;
    }else //The cooldown has expired. Put it back to original, and attack.
        cooldown = mc.thePlayer.getCooldownPeriod(); //mc refers to the Minecraft object. getCooldownPeriod() returns the cooldown period of the item held by the player.

    //Loops through all loaded player entities, checks whether they're alive or not, and attacks them
    for (Entity entity : mc.theWorld.playerEntities){
        if (entity.isEntityAlive(){
            //Attacks the player using a packet
            mc.thePlayer.connection.sendPacket(new CPacketUseEntity(entity));
            mc.thePlayer.swingArm(EnumHand.MAIN_HAND);
        }
    }
}