I just wanted to put an official response here for people that search in the future. There was a question about whether or not you could use Erkenbrand's ability with damage cancellation like Honour Guard or Raven-Winged Helm. Here is the official answer:
When a player uses a Response to cancel an effect, the result is that the canceled effect never resolves. For example, when a player uses A Test of Will to cancel the ‘when revealed’ effects of The Necromancer’s Reach, the players do not deal 1 damage to each character in play and then remove 1 damage from each character in play. Instead, no damage is dealt.
Similarly, if you use the Response effect on Raven-winged Helm to cancel the damage just dealt to Erkenbrand after triggering his Response effect, you do not place 1 damage on Erkenbrand and then remove it. Instead, the damage is not dealt at all. In which case, his cost has not been paid and you cannot resolve his effect.
Visually, it looks like this:
Damage is dealt by effect ——> Response effect cancels damage dealt ——> No damage is actually dealt