When you think of Headstone Carver, you're probably thinking of the usual Neptuna brutality. But, let's say you'd rather play Impfinity today. that gives you access to crazy and sneaky, which is the only way this combo gets played (absent random accidental combos via Brainstorm or Tomb Raiser or whatever).

So, your Exploding Imp is a 6/1 smackdown, that does 1 damage to itself at the end of every turn. to really make the Exploding Imp work, you also need to mix it in with some stuff that the enemy isn't going to want to block, or alternately isn't going to want to block with weenies. Newspaper Zombies are a great choice here--if they block with a weenie because they expected a bomb, they instead build you a bomb.

Headstone Carver boosts it up to a 7/2, which also means that if it gets to attack in an empty lane it will survive to strike again. Plus, because the bomb 'hatches' after the plant has gone, there's not a lot they can do to stop this pain. Smoke Bomb or Backyard Bounce are your friend here.

"But wait", I hear you saying, "why not just use the Stealthy Imp?" Well, there's no reason you can't use both, but the main advantage of the Exploding Imp is that it doesn't rely on anti-hero for the power, meaning that there isn't really a way you can block it off and kill it without dying. The most advantageous trade you can make against an Exploding Imp is to use denial on a creature that was going to die anyway, or to sacrifice a weenie on it. Exploding Imp is also excellent for lane clearing because it knocks a hole in the enemy's line, and then promptly gets out of the way to allow you to drop something else into that hole. Given how much sneaky decks rely on various things hitting the enemy hero, this is actually a massive benefit.

TL;DR: Getting a second hit out of an Exploding Imp thanks to Headstone Carver is damn solid for an Impfinity deck.

Edit: Repost to fix which thing I'm talking about.