Explosive Runes vs Divine Shield

Hi, in current Tavern Brawl my opponent mage played an Explosive Runes secret then I played Flutterwing Guardian. Explosive Runes hit the minion, didn’t damage it and removed divine shield, but then it hit me for 2(6-4 with 4 health from minion I suppose) damage. Shouldn’t it be 0?

No. Explosive Runes calculates its damage to the minion and the hero based on the minion’s current health. It doesn’t know, or care what effects are on the minion.

So your minion has 4 health and Explosive Runes deals 6. It splits that damage and directs 4 at the minion (absorbed by Divine Shield) and 6-4= 2 to the hero.

This isn’t a bug.

That’s how excess damage works in Hearthstone, as non-intuitive as it is