Example

gremlins.createHorde()
    .before(function(done) {
        var horde = this;
        setTimeout(function(){
            horde.log('async');
            done();
        }, 500);
    })
    .before(function() {
        this.log('sync');
    })
    .gremlin(gremlins.species.formFiller())
    .gremlin(gremlins.species.clicker().clickTypes(['click']))
    .gremlin(gremlins.species.scroller())
    .gremlin(function() {
        alert('here');
    })
    .after(function() {
        this.log('finished!');
    })
    .mogwai(gremlins.mogwais.alert())
    .mogwai(gremlins.mogwais.fps())
    .mogwai(gremlins.mogwais.gizmo().maxErrors(2))
    .unleash();

https://github.com/marmelab/gremlins.js