No it was a card game in its own right, not an expansion pack for Spellfire. It even had a couple expansion packs of its own.
It was released in a Dual-Deck format so that 2 people could play with just one purchase, and then supported by an expansion pack (Rebels & Reinforcements) made up of cards from the DD release plus 34 chase cards.
Later another two expansions (called Escalation packs) were released: Factols & Factions brought the city of Sigil into the war, and Powers & Proxies added in many of the gods.
There was also the Warlord's Tactical Manual released, which was a more comprehensive version of the standard rulebook, plus tips and tricks for deck building and strategy, plus a very useful picture guide to every card from the intial release and all the expansions.
3 more Escalation packs were planned, though I only know the name of one of them (Insurgents of the Inner Planes) but the line was cancelled. I have LOADS of these cards. In all there were 603 cards released for the game. I think I'm missing about 80 to complete my collection.
Looking at the picture of Faaram's card shows him as a Unique Death Slaad. He added 1 CS (Combat Skill) to each Legion in his Battle Hand (stack).