His ultimate is automatically triggered once his health drops below 400HP.
Therefore it is a passive and an active (if you want to it to be). However, if you deal more than 400 damage to an illusion, it won't trigger (assuming this is a killing blow I mean.)
Put Troll in Bag
Originally Posted by Cobnox At first I thought fountain shoot meatball.
In dota illusions could not benefit from it. (Because the trigger stores units that learn the ability for first time and does stuff for those units only)