Is it possible to react to Targon's Peak activation at the end of the turn?

Ruling: Yes, there are two possible points to react to Targon's Peak. You can respond to the initial "When you conquer" trigger right after someone conquers it, and you can respond to the delayed ability when it gets added to the chain at the appropriate end of turn time. However, neither reaction point will prevent the conquering player from readying 2 runes.

Sequence:

• First reaction window: When the "When you conquer" trigger occurs (this only adds the delayed ability)
• Second reaction window: At end of turn when the delayed ability is added to the chain

Nuances:

• End of turn is normally not a phase where players can play spells or activate abilities, but the delayed trigger creates a window for reaction-keyworded spells
• The trigger happens even if there are no runes to ready or if runes are already ready
• Ready runes are valid targets, and "up to" means 0 runes is also valid