Shadowwalker

The Shadowwalker is a Keyword equivalent to the following effect:

You can choose another face-down creature you control; flip this back face-down and switch their positions. You cannot activate more than one Shadowwalker effect per chain.

Rulings

[this] is not considered to have been summoned or flipped.
Do not trigger "When summoned" or other "When flipped" effects for [this]
Do not collect mana for the summon of [this].
Flip, summon and resolve any associated effects of the chosen replacement.