any DoT can be direct damage if the champ kit is made so ...it just means there wont be debuff icon ticking down...just means it will be a burst of red damage in one tick..knull does bleed damage as a direct damage once he enters corruption mode...doesnt mean bleed is a direct damage.. fury deals bleed as a DoT so you will see a bleed debuff ticking down ...same way shock is a debuff but guardian deals shock as direct damage when he crits ....