The cost of each new style will depend on the cards rarity: Commons : 400 Gems (approximately $2.50, since 1,600 gems cost $9.99) Uncommons : 600 Gems (approximately $3.75) Rares : 1000 Gems (approximately $6.25) Mythic Rares : 1,200 Gems (approximately $7.50) Importantly, each new card style is only applicable to cards with the same art as as the card style
I'd recommend a few of the guild signets from Ravnica, Arcane Signet and Farseek
Depending on the type of deck you are building, be it reanimator or otherwise, you may want to run each of these kinds of cards
This sorcery is pretty swingy, and its effectiveness really comes down to the individual guile of the players involved
Its a nice reminder that there are other ways to bolster Modern outside of printing brand new cards, and that the ability to pull cards from Legacy and even Vintage suggests the next Modern Horizons set could have players shouting in the streets with excitement