323.4. 3a. All Units that have Lethal Damage marked on them and that have Deathknell or other abilities that trigger on their own death will trigger such abilities now, making note of their current location, attributes, and other information relevant to add the trigger as a Pending Item See rule 808 Deathknell for more information.
323.5. 3b. All Units that have LethalDamage marked on themare killed and placed in their owners' Trash. See rule 142.4. For more information on lethal damage.
323.6. 4. Players lose control of any controlled Battlefields without their Units occupying them if the turn is in an Open State and there is no Showdown or Combat ongoing there.
323.7. 5. Recall all Unattached non-Unit Gear and non-Unit Runes at Battlefields, and all Permanents and Runes in Bases other than their controller's. Remove all Hidden cards from all Battlefields that are not controlled by the same player and place them in their owner's Trash.
323.10. 7a. If Units of two opposing players are no longer present at a Battlefield that has a Combat Staged before it has opened, the Combat will cease being Staged
323.12. 9. If the current state is a Neutral Open State and one or more Showdowns are Staged at Battlefields without a Combat staged, the Turn Player chooses one of those Battlefields. A Showdown begins there.
323.13. 10. If the current state is a Neutral Open State and one or more Combats are Staged at Battlefields, the Turn Player chooses one of those Battlefields. Combat begins there.
323.14. 10a. If the current state is Showdown Open State and Combat is Staged at a Battlefield where there is a Non-Combat Showdown ongoing, that Showdown becomes a Combat Showdown.