The ability won't affect those spells and it won't affect spells that those players cast before you activated it
Oviya Pashiri, Sage Lifecrafter: Solid incremental rare
Spiritmonger was about there being no way out, other than killing the player
Second, this increased cost often means multicolor spells cant be cast as quickly or easily as a monocolor ramp spell especially if you arent able to assemble multiple colors of mana due to a poor opening hand or early disruption to your mana
Friends On The Other Side is basically a must-have in all Amethyst decks too

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