When Retreat targets a unit that gets killed by another effect on the chain before Retreat resolves, does Retreat's owner still get to channel a rune?

Ruling: Retreat will resolve to no effect because its target unit is no longer on the board, which returns a null value for "a friendly unit" and therefore won't allow the owner to channel.

Sequence:

• Stupify 2 resolves first, killing the unit that Retreat and Stupify 1 had targeted
• Retreat attempts to resolve but the targeted unit is no longer valid since it's out of play
• Retreat returns a null value and cannot find "its owner" because there is no valid unit reference
• The owner does not get to channel a rune

Nuances:

• Owner refers to the player whose deck the card started in
• Controller refers to the player who has control of the card at that moment (usually the owner, but some effects allow taking control of opponent's cards)