On xbox one, during PvP-
When Ubastet kills two people, if the second troop to get hit has a summon on death perk, Ubastet will automatically kill the summoned troop, in total killing 3.
It only happens when the second troop to get hit has the summon perk, not the first.
Here’s a gif from an xbox recording. https://giant.gfycat.com/FittingWealthyJackrabbit.mp4