Rulings

If you give double strike to a creature with first strike after first-strike combat damage has been dealt, that creature will also deal damage during the normal combat damage step.
If you give double strike to a creature after either first-strike or normal combat damage has been dealt, it won't help that creature deal any additional combat damage.

Artworks (1)

Sunhome, Fortress of the Legion
Martina Pilcerova

Open detail