Quote from PhroX »Goes well in voltron type decks in general - outside of Finest Hour it's probably the best extra combat spell for the decks where you're only swinging with one creature.
Particular synergies with Xenagos, God of Revels (hit for 14x base damage) and Neheb, the Eternal (gives you increasing amount of mana each main phase, part of which can be used to pay for this) along with any mass vigilance enablers, which turn this into a flashbackable Relentless Assault.
If you could combine mass vigilance with Zada, Hedron Grinder, this would be disgusting, but off the top of my head I can't think of ways to do that in mono-red (Akroma's Memorial gives prot/red), so thats probably just for those odd General Tazri 5-colour Zada decks.
Wait, doesn't this target? Targeting Zada would untap your whole team. Of course you'd need vigilance to take advantage of all the extra phases beyond the first, but she still makes it a flashback able relentless assault as it is.