Spoiler time!
Structural Assault
Imagine the following boardstate: You have drawn poorly since your somewhat slow starting hand and have fallen behind at the start of the game. Your opponents have a Sol Ring, the occasional signet, a troublesome piece of equipment and some other artifact lying around, along with some green elf that creates mana and maybe a few to medium-sized creatures... You still sit with a smile on the corner of your mouth and glancing back at your hand to confirm that you really have a handle on what you have. You realize you were right and shuffle the cards back and forth so that the clatter of the plastic pockets makes the player on the right look at you a little sideways and sigh. The tour is tailored to you. You tap your lands confidently and draw a card you don't really care about - you know what to do this turn. You lay out your foiled full-art Mountain from Unhinged and drop five lands and play:
Structural Assault
3RR for a sorcery that destroys all artifacts in play, then deals damage to all creatures for each artifact in the graveyard during the same turn.
4-5 artifacts go into the grave and all creatures take the same amount of damage. You've reset the board and given yourself a chance to get back into the game. Your opponents mutter something inaudibly and collect their permanents and place them in the grave. The smile on the corner of your mouth has been replaced by ill-concealed glee and you triumphantly pass the turn to the next player.
In Standard, we think this will be a safety valve against artifact decks that mix cards from Kamigawa with the Fall: Brother's War set (where we suspect a lot of big artifacts will appear). Either for Grixis control variants or it could prove to be a more general sideboard card for more decks than that. It's possible that the effect of dealing damage to creatures won't be that important, but it's a bonus that small creatures used to jump into Vehicles are cleaned up smoothly.
In Modern, there are several artifact-based decks currently, and even if Urza's Saga isn't an artifact, this card will destroy anything that Saga produces for three turns. Other slower Artifact decks built around Urza, Lord Hight Artificer can also get into big trouble with Structural Assault. There are other, cheaper options in Modern to destroy all artifacts - but in the right meta there is still a small chance of playability...?
Regardless of how the card turns out, it's fun to have been given the chance by Wizards if the Coast to show off the card to the world and we will be playing the card ourselves in every red game ;)
Have a great time!
/The spoiler cod