If I Lotus Trap a card twice, does it take 4x damage?

No, using Lotus Trap twice on the same unit does not result in 4x damage.

Lotus Trap creates a replacement effect that doubles the damage a unit would take. If you apply two separate instances of the Lotus Trap effect to the same unit, they are both active. Because each is a separate replacement effect that says "double the damage," they apply sequentially to the incoming damage:

1. First Effect: Doubles the incoming damage (x2).
2. Second Effect: Doubles the result of the first doubling (x2 * 2 = 4x).

Therefore, applying two Lotus Trap effects to the same unit makes that unit take 4x damage, not 4x the base amount in a way that implies additive bonuses.

Important Considerations:

• Replacement Effects: These effects are applied in the order they are resolved.
• Cumulative Nature: Because these are distinct replacement effects, they do indeed compound to create 4x the damage.

This is my interpretation based on the mechanics of replacement effects in Riftbound. No official FAQ exists for this specific interaction.