Do units added to a battlefield (or revealed from hidden) during showdown participate in combat?

Ruling: Yes, units revealed from hidden or added to a battlefield during showdown fully participate in that showdown and contribute to combat damage.

Sequence:

• The unit is revealed/added during showdown
• The unit is fully resolved as part of that showdown
• Combat damage is calculated after the showdown is complete
• The newly revealed/added unit's damage is included in the total