If I give Hidden Blade Repeat, and I choose the same unit with both instances, will its controller draw 4 cards instead of two?
Yes, if you successfully play Hidden Blade with the Repeat keyword and choose to pay the Repeat cost, you would draw 4 cards only if the target unit remains a valid, legal target at the battlefield for both separate executions. If the unit dies or is moved after the first execution, it becomes an invalid target for the second, and the draw effect for the second execution will not trigger.
According to Rule 820.1.d, the Repeat keyword is shorthand for: "You may pay [Cost] as an additional cost as you play this spell. If you do, execute the instructions of this spell one additional time."
Sequence of Events
- Playing the Spell: As you play Hidden Blade, you declare you are paying the Repeat cost. You choose a unit for the first execution and a unit for the second execution (these can be the same or different).
- Resolution: When the spell resolves, it executes its instructions twice.
- First Execution: Hidden Blade kills the target unit and its controller draws 2 cards (Rule 820.1.d.1).
- Second Execution: The instructions are executed again. Hidden Blade attempts to kill the target again and its controller draws another 2 cards.
Important Considerations
- Targeting: As noted in Rule 820.2, you make choices for each execution separately at the time the spell is played. If you choose the same unit for both, the first execution will kill it.
- Resolution of the Second Execution: If the unit is killed by the first execution, it is no longer on the battlefield for the second execution. Per Rule 359.3.e.6 and the associated FAQ regarding Hidden Blade, if the target is no longer on the battlefield, the instruction regarding that target is ignored. Consequently, if the unit was killed by the first execution, the second execution will be unable to find the unit to perform the "kill" action or determine "its controller," and no additional cards will be drawn for that second execution.
- Replacement Effects: If the target is saved by a replacement effect (e.g., Zhonya's Hourglass or Sett) during the first execution, the unit must still be a valid target on the battlefield for the second execution to resolve and draw cards.
Note: I could not fully verify the interaction with replacement effects against the retrieved rules.