Re-read the card. It doesn't expire; it's a suppression cloak for your artifacts. And it can come as a surprise the first time. If you counter an opponent's spell with it, it pays for its own tempo (and likely its own mana), then sits around draining mana until it's dispelled.
It's a 2-for-1 in both mana and tempo if it catches the first dissolve, then catches a dispel.
And I really wouldn't want to try dispelling high cost artifacts through one of these. 8+4 is 2 turns of mana for an opponent's agro deck, where 8 is only 1 (assuming he's spending to 0 every turn).
It's an enchantment, so it works with Enchanter's Ring, and it's meta magic, so it works with Arcane Ring, and it's Holy, so it works with Ring of Asyra. It's got a "protection" keyword, too, which I'm sure will be useful soon enough. It protects against abilities that destroy artifacts, not just spells (Druid?).
It's protection for your wands that can't be baited with a Decoy (Nullify) or Arcane Zap (Jinx), and it's compatible with Nullify so you can stack both.
The major downsides I see are a hefty spellbook price for Warlock (5 points), and Wizard when compared to Nullify (4 vs 1). If agro Priestess (or Priest) is a thing, Armor Ward plus Battle Forge seems like a pretty good way to start. Oh, and it's actually the same spellbook price as Nullify for Warlord!
The more I look at it, the more I love all the design details in this card. I'm not certain it's good (might be kinda situational, requires playtesting) but damn if it isn't beautiful.
Will it prevent the attack from an Explode? I'm thinking no (a shame) but it might, depending on what is meant by, "Destroy the chosen equipment. Then Explode makes the above flame attack against the target Mage."