Mysteries of the Deep

Instant

Draw two cards.
Landfall — If you had a land enter the battlefield under your control this turn, draw three cards instead.

2010-03-01:
Whether you had a land enter the battlefield under your control this turn is checked as this spell resolves, not as you cast it.
2010-03-01:
Having more than one land enter the battlefield under your control this turn provides no additional benefit.
2010-03-01:
The landfall ability checks for an action that has happened in the past. It doesn’t matter if a land that entered the battlefield under your control previously in the turn is still on the battlefield, is still under your control, or is still a land.
2010-03-01:
Once the spell resolves, having a land enter the battlefield under your control provides no further benefit.
2010-03-01:
The effect of this spell’s landfall ability replaces its normal effect. If you had a land enter the battlefield under your control this turn, only the landfall-based effect happens.