Can you react to Mobilize (a card that generates resources)?

Ruling: Yes, you can react to Mobilize with a reaction spell. The opponent playing Mobilize starts a chain, giving you an opportunity to react.

Nuances:

• The restriction on reacting to abilities that add resources only applies to abilities with the Add keyword (like Lux tapping to add energy or Kaisa legend tapping for power)
• Mobilize does not have the Add keyword, so it can be reacted to
• Runes are not resources; energy and power are resources