If a unit with a defend ability gets moved to a battlefield during a showdown after the initial attack/defend triggers have resolved, does the defend ability still trigger?

Ruling: Yes, when a unit moves to a battlefield during a showdown, they receive appropriate designation and their "when I defend" abilities will trigger if it's the first time that combat they receive defender designation.

Sequence:

• Unit moves to battlefield during showdown
• Unit receives defender designation in the next step
• If this is the first time this combat the unit receives defender designation, "when I defend" abilities trigger

Nuances:

• The ability only triggers if it's the first time that combat the unit gets defender designation (not if they previously had defender, moved away, lost it, and moved back)
• This allows "double dipping" on defend triggers with effects like Ezreal's signature spell, since a newly played unit is technically a "new" unit