I'm giving you credit for the card you made, he simply warned that the fae wouldn't be civil around this group of druids and future rangers.
Think around how a duel would work, roleplay style. Stored manna, however, means the Alencians can reserve tapped manna for later use - unlimited turns.
So, with all that manna flowing, they are definitely in a good position to start negotiating with the Eldraine forces.
November 24