Orbital Bombardment
From Archon Arcana
Orbital Bombardment • Mars • Action • Uncommon • Play: Reveal any number of Mars cards from your hand. For each card revealed this way, deal 2
to a creature. (You may choose a different creature each time.) • Artist: Ameen Naksewee • Card Number: CotA (172), AoA (185)

Commentary
All of the damage done by Orbital Bombardment would be done simultaneously.
Source: Damage
When resolving the ability of Orbital Bombardment, "any number" can be treated as zero.
Source: Play (step)