Can you use foreign language cards in Riftbound, and are there any restrictions on mixing languages?

Ruling: You can play any language cards in any region (the game is not region locked). Your Main Deck and Side Deck must all be in the same language as each other, and all Runes must be in the same language as each other, but the Rune language does not need to match the Main/Side Deck language.

Nuances:

• Main Deck and Side Deck must be the same language
• All Runes must be the same language as each other
• Runes can be a different language than Main Deck/Side Deck