And They Shall Know No Fear It looks like a simple combat trick, but in typal decks, And They Shall Know No Fear is an almost better Heroic Intervention
If youre saving mana by casting one of these spells for free, thats another spell towards your storm count to get a bigger Empty the Warrens, Grapeshot, or Tendrils of Agony
Add warp to the mix, and youve got a repeatable engine that piles on advantage while it flies over the battlefield
"Formats"
Virulent Sliver would come in development when the sliver cycle (common slivers that each share a new keyword with its brethren) was added
Since all the combos require my commander to instantly win, a quick n' easy way to do this would be just to swap Niv-Mizzet, Parun out with a noncombo commander and call it a day: Niv-Mizzet, Dracogenius is a straightforward swap if you still want to keep The Firemind in your command zone, or you can switch to another Spellslinger commander like Kaza, Roil Chaser