Combat damage this deals to units or heroes, even to their armor, kills them.

Deathtouch Rulings

Anything that checks for "dying from combat damage" such as Brave Knight or Gilded Glaxx does "die from combat damage" if deathtouch hits it.Sirlin, 03/11/16
Deathtouch does not stack. Having two instances of deathtouch is the same as having just one.sharpo, 09/16/16