Saint Louis Park
Rulebook Page 25 wrote:
Many cards are written in a “pay or exhaust X to do
Y” manner. When confronted with such a construct,
everything before the word “to” is considered the cost,
and everything after the word “to” is considered an
Action: Discard 1 card from your hand to give Eowyn +1 Willpower until the end of the phase. This effect may be triggered by each player once each round.
The cost is "discard 1 card from your hand." The effect is "give Eowyn +1 Willpower until the end of the phase."