When Stormbringer deals lethal damage to Viktor Leader Champion and another unit simultaneously, then moves the attacking unit to that battlefield, what is the correct sequence of resolution, including when units die, when Hidden Blade is removed, and whether Viktor's ability triggers?

Ruling: Stormbringer resolves completely (damage then move) before cleanup occurs. Viktor does not trigger because he dies simultaneously with other units during cleanup, and triggered abilities only check after cleanup completes.

Sequence:

• Stormbringer is played, opponent can react with Hidden Blade
• If no reaction, Stormbringer resolves: deals damage, then moves the unit to the battlefield
• After spell resolution, cleanup occurs: units with lethal damage are put into trash, and Hidden Blade (now on a battlefield controlled by a different player) is put to trash
• After cleanup, triggered abilities would check, but Viktor is already in trash and does not trigger
• Non-combat showdown begins since the moved unit is now contesting the battlefield

Nuances:

• Viktor Leader Champion never triggers if he dies at the same time as other units
• Hidden Blade can be used in reaction to Stormbringer being played (before it resolves) to kill a unit and draw cards
• Hidden cards on a battlefield controlled by a different player are removed during cleanup