Here is a nice exploit that will allow you to basically get the perks of earth shake buff and consume the attack charges. its pretty amazing right now for PvP
(!empty($user->lang['QUOTE'])) ? $user->lang['QUOTE'] : ucwords(strtolower(str_replace('_', ' ', 'QUOTE'))):
as a riftblade/champion warrior, if you use [punishing blow] followed by [earth shake] less than a second later, [punishing blow] will consume the attack charges but you will gain the [earth shake] buff, this might be because of server lag, i do not know. all i know is it rips !@#$%^&* up in pvp.