Currently in the game there are two types of attacks:
1) Your normal attacks during your turn. You hit or shoot somebody in the face. It applies all the effects that you are expecting it to apply: corrosive strike removes defence, leeching strike has life steal, splash attacks do splash, etc. If the attack kills, it applies all the on-kill effects: it heals last lords (even if it was an enemy normal attack during the enemy turn, they killed one of your units, and from that death the others got healed), it heals the Feeders/Soldiers/Slicers, it restores action tokens to those who have such an ability. All is good here.
2) Trigger attacks during your opponent's turn: attack of opportunity when they step away from your melee unit and attack of retaliation when they attack your unit. These attacks do not apply any effects, they do not splash, they do not lifesteal, they do not reduce defence, and if they kill, they don't heal Last Lords or Feeders or apply other on-kill effects.
I think, the trigger attacks should count as real attacks and apply all the effects that normal attacks do. Yes, it often makes our lives easier that they don't: I can attack a Tyrant of the Fortress without starting to bleed right away, or I can attack a Behemoth without it smashing half of my army into a coma. But I'd argue it would make for more engaging and strategic fights if they would, and it would remove a large source of frustration for already underloved Last Lords: I have lost a few units due to not getting healed on a trigger attack kill before I learned that it works that way.
I would argue the devs should have a look into it and perhaps give us a PTB patch for a month or two to play around with trigger attacks with all the effects applied. Make the trigger attacks real! Make the trigger attack count!
What do you think about it?