I used to have Anger of the Gods, and way before that, Flamebreak in my cube. The idea of mass removal for weenies seems like a great card to run along with the Wildfire/Burning of Xinye strategies. This can be especially true when you commit to the archetype and you end up with more X/4's than X/5's.
Sweltering Suns does for Anger what Wilt did for Naturalize: the option to dig into your library when the card is a dud. Cycling really does take a card that, while great, can be situational, and turns into a card always worth running because of the card's built-in contingency plan.
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Shattering Spree has not aged well for me.
Vandalblast and Abrade offer more options and are less demanding for mana. If I do find that I need more artifact removal, I'd probably opt for Shenanigans or an ETB creature like Manic Vandal and/or Oxida Scrapmelter.
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Harness by Force doesn't get played. A 1RR Act of Treason isn't good, and while a 3RRR card that "Act of Treason's" your opponent's two best creatures sounds impressive on paper, but in practice, you're much better off playing a heavy hitter on turn 6 that borrowing someone else's for a turn.
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Past in Flames has been on my radar since I started looking at more options for "spells from graveyard" types in blue, black and red. Blue has cards like Snapcaster and Gearhulk to take advantage of instant and sorceries in the graveyard. Cards like Yawgmoth's Will let you play anything from your graveyard for the turn. Red gets Underworld Breach and Mizzix's Mastery, and now Past in Flames to support the idea of playing spells twice instead of once. This card may be a little underpowered now, but once I add in more fast mana (i.e. Cabal Ritual, Pyretic Ritual and Desperate Ritual), I think cards like Past in Flames will work quite well in my cube.