Does Ravenborn Tome's effect persist until next turn, or does it expire at end of turn?

Ruling: The effect is assumed to last until end of turn, even though the card text doesn't explicitly state "this turn" or "end of turn."

Nuances:

• The card text appears to be missing "this turn" language in both English and Chinese versions
• The effect is likely intended to expire at end of turn rather than persist indefinitely
• The next spell played would consume the effect, whether or not that spell deals damage