Rule 445.2
When a player is instructed to Pay a resource, that player may remove that resource from their Rune Pool if it exists there. If they choose not to, the instruction is negated.
- 445.2.a If the instruction to Pay resources is part of paying costs for a card or ability, choosing not to pay those resources…
- 445.2.b If the instruction to Pay resources is part of paying any other cost, choosing not to pay those resources will prevent…
- 445.2.c Players may activate abilities that Add resources with the Reaction keyword at any time that they are instructed to…