When Sett Kingpin is saved by his legend ability after combat where all units die, does his buff disappear before or after other units die, and can Vanguard Helmet transfer a buff from a dying unit to the recalled Sett?

Ruling: Yes, Vanguard Helmet can transfer a buff to Sett when he is recalled via his legend ability. The other unit dying and Sett being recalled happen simultaneously, triggering Helmet's ability which can then target the recalled Sett.

Sequence:

• Both units receive lethal combat damage and cleanup would kill both units
• The Legend ability allows you to replace Sett's death with a recall by recycling a rune and exhausting the Legend
• If you elect to replace the death, the other unit dies and Sett gets recalled simultaneously
• Helmet's ability triggers and is put onto the chain since it saw the other buffed unit die, and you announce Sett as the target
• If it resolves, Sett gets the buff