I dont know if casting this Sephiroth variant will be viable in Final Fantasy Limited, but know that doing so is well worth the effort
Because replacement effects are considered before Purphoros is on the battlefield, the mana symbols in its mana cost won't be counted when determining this
Rite of Harmony is a cheap sorcery that represents the druidic wisdom of the Elf tribe
The other option is to take advantage of the direct damage, which is good in its own right to either finish off a damaged character or get them within range to be banished but also works with the likes of cards that benefit from being damaged - such as Scroop, Backstabber - that benefit from healing damage, like Rapunzel, Gifted Artist, or from damage being dealt: like Beast, Relentless.
Likewise, Tamatoa - Happy as a Clam is another great Item-focused Sapphire card, much like its predecessor, Tamatoa - So Shiny