Let's look a bit more into the new "cards under cards" ruling.
We have a ruling that a card under another card has no text, and that that does not stop destruction response triggers that move under another card.
So let's look at Explosives Wagon.
our ruling on it is that it stays in play to deal its damage, but that ruling is now being altered by the new ruling.
Now wagon can go under Savage Mana and still act.
So we get interactions like:
1. Is the static bonus to damage still in effect? That used to be a simple ruling that yes, it was in effect because the card is still in play. Now the card is still in play, but it has no text, is it still boosting damage?
2. Is it still a target? It has no text, it is not a target, right? So now Environmental Allies, Grease Gun, cards like that no longer affect it. What about Stun Bolts? Throat Jab? They both specify that the Target cannot deal damage, but that target has left play, if a bounty was on the card it would trigger, Wrest would leave play, and effects that affect targets would no longer affect Wagon.
But it is still dealing damage.
I personally find these 2 rulings to be ridiculous, because they create interactions like this as valid play options.
And thematically, What the heck is going on that Haka just ate something, and then it explodes? that is absurd. We are in Bugs Bunny territory.