That doesn't feel like it will often help. I.. guess if you have a different creature with first strike, and the power lines up, you can have that creature kill rather than this one. Or double the damage of an unblocked first-striker. But that really just means an opponents blocking choices get more complicated. And needs you to be running almost nothing but first strike.

@Vitenka you don't need to target a creature that already has first strike... Since this deals combat damage before creatures without first strike, the idea is to give your opponent the choice between letting 3 damage go through, or blocking it and potentially doubling the damage of a different attacking creature.

It needs to target a creature with first strike for it to double the damage on anything, which is his point. By the time this ability triggers, the first strike damage step will already have happened, so double strike is just "normal strike" at that point.

I guess the rare circumstance of a second combat step could make it relevant - but yeah. By the time spare happens, first strike is over.

Yeah you're right... I could change it to gets +X/+X and that would work in the way I want it to