User blog comment:Typhron/Tess, Inciter of the Sands/@comment-1330314-20121126211359/@comment-1330314-20121126232730

If you want to let players detonate her Q manually, you could always have the DoT/HoT apply a passive debuff/buff which'd be consumed upon detonating her ability, which'd also work well with Tess as a support. For example, it could reduce damage taken on allies and increase damage taken on enemies (though, obviously, that is not the only option out there).