Flying
Whenever Seraph of New Phyrexia attacks, you may sacrifice another creature or artifact. If you do, Seraph of New Phyrexia gets +2/+1 until end of turn.
Any player may respond to Seraph of New Phyrexia’s triggered ability, but once that ability starts to resolve, no player may take any actions between you deciding to sacrifice another creature or artifact and Seraph of New Phyrexia getting +2/+1.