Who goes first, Barron Geddon or First-Aid Kit?

In Hearthstone, Barron Geddon's card text says "At the end of your turn, deal 2 damage to ALL other characters." Meanwhile, the First Aid Kit passive says "At the end of your turn, restore 2 Health to all friendly characters."

Which one happens first, at the end of the turn? Does Barron Geddon first deal 2 damage to everyone, then First Aid Kit restore 2 health to all friendly characters? Or does it happen in the opposite order?

Solution 1:

Generally speaking, Hearthstone cards resolve in order of play. As passive cards are cast at the beginning of the game, a First Aid Kit will always be played before a Baron Geddon, so the heal effect will happen first.

This means that one- and two-health minions will die to a Baron Geddon played while a First Aid Kit is active, as opposed to the opposite case, where they would survive.

For more details, you can read the advanced rulebook.