Does Viktor trigger his ability when he is the target of Retreat (returning him to hand)?

Ruling: Viktor does not trigger when Retreat is played on him. Viktor only triggers when a spell is fully resolved and only if he is still on the board when that resolution happens. Since Retreat returns him to hand before the spell resolves, he is no longer on the board to trigger.

Sequence:

• Retreat is played targeting Viktor
• Viktor is returned to hand
• Retreat finishes resolving
• Viktor does not trigger because he is not on the board when resolution completes

Nuances:

• A card is only considered "played" when it resolves, not when it is cast