It’s supposed to damage an ally and heal him, but apparently it can also target dead allies, not dealing damage to the living one.
Agreed. This is repeatable - if both allies are still alive, one will take damage, but if one is downed, sometimes no damage is dealt.
I saw this as well. The live ally didn’t get hurt. Presumably the damage only hit the dead ally.
I’ve always thought that he shouldn’t be able to cast this skill if he has no allies left, but that’s probably not considered a bug.
agreed. I didn’t even put it all together in my mind that he was “sapping” from the dead opponent, I just assumed the game was broken and he was healing himself without hurting his own ally. Kind of annoying, I usually like to let Konran down his own ally with this move.
I thought so the same, but if you read the description of the ability (as far as I remember) it doesn’t say the that he won’t heal himself if there are no allies. Someone correct me If I’m wrong here 
If there are no allies, he’s always healed himself without dealing the associated damage. If there’s one ally, he’s supposed to damage that ally. I think the current problem is his damage sometimes targets the downed ally, allowing him to heal without damaging his remaining comrade.
I always thought the description said that he grabbed an ally and drained life force or health from that ally. Thus healing himself and hurting his ally. That’s why I was confused how he can heal without any team mates.
Confirm: sometimes he targets a dead ally, so he doesn’t damage anyone 