When Karthus creates additional triggers, do they all go on the same chain at once, or does each trigger resolve before the next is added? Can players react to each trigger separately?

Ruling: Both triggers go on the same chain at the same time, with the controller ordering them. Players can react before either resolves, or let one resolve then play a Reaction before the other resolves.

Sequence:

• Both triggers are added to the chain simultaneously (or one creates the chain and the other is added to it)
• The controller orders the triggers
• Players can react before either resolves
• Alternatively, players can let one resolve, then react before the other resolves

Nuances:

• Since the triggers are the same, the order chosen by the controller typically shouldn't matter
• Players cannot react to each trigger individually as they are added, since they go on the chain at the same time